1

z/OS

Introduction

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The new mainframe Mainframe facts 05

Typical batch use 08

Typical online use 10

IBM System z Parallel Sysplex 11

LPAR 14

z/OS

What is z/OS 16

Hardware resources managed by z/OS 17

Virtual storage and address space concept 18

z/OS address spaces 20

Interactive facilities of z/OS: TSO/E and ISPF

How do we interact with z/OS? 23

General structure of ISPF panels 25

Option 1 VIEW 26

0Option 2 - E D I T 28

Option 3 UTILITIES 29

Working with data sets What is a data set? 31

Data set record formats 33

Types of data sets 34

Locating a dataset in MVS - Catalogs and VTOCs 37

Data Facility Subsystem Managed Storage (DFSMS) 39

VSAM 40

Using Job Control Language (JCL), System Display and Search Facility (SDSF) and JES JCL 43

Batch flow (simplified) 46

SDSF: Primary option menu 48

SDSF: Status panel 49

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Transaction managers on z/OS Example of online processing: a travel agency 50

CICS in a z/OS system 52

Languages & Platforms 53

BMS macros 54

Example of CICS application user screen 55

Database Manager on z/OS

Database Manager on z/OS 57

Example of a DB2 Department Table 58

DB2 Administration (transactional interfaces) 59

SPUFI 60

Security on z/OS

Security on z/OS - RACF 62

User Identification 64

4

Unit 1

The new mainframe

Who uses mainframes? Most Fortune 1000 companies use a mainframe environment 60% of all data available on the Internet is stored on mainframe computers

Why mainframes?

Thousands of transactions per second Support thousands of users and application programs Simultaneously accessing resources Terabytes of information in databases Large-bandwidth communications

Consolidation of mainframes Many installations used to have several boxes A single larger machines running many LPARs is often more cost effective, as software

licenses for multiple small machines can total more than those for a single large one

Mainframe facts

Notes: JCL is used to describe the work you want a system using multiple virtual storage (MVS) to perform.

7th April 1964, Poughkeepsie NY A new generation of electronic computing equipment was introduced today by International Business Machines Corporation. IBM Board Chairman Thomas J. Watson Jr. called the event the most important product announcement in the company's history.

The new equipment is known as the IBM System/360.

"System/360 represents a sharp departure from concepts of the past in designing and building computers. It is the product of an international effort in IBM's laboratories and plants and is the first time IBM has redesigned the basic internal architecture of its computers in a decade. The result will be more computer productivity at lower cost than ever before. This is the beginning of a new generation - - not only of computers - - but of their application in business, science and government."

System/360 offered a choice of five processors and 19 combinations of power, speed and memory. A user could operate the same magnetic tape and disk products as another user with a processor 100 times more powerful.

System/360 also offered dramatic performance gains, thanks to Solid Logic Technology - half-inch ceramic modules containing circuitry far denser, faster and more reliable than earlier transistors.

System/360 monthly rentals will range from $2,700 for a basic configuration to $115,000 for a typical large multisystem configuration.

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Comparable purchase prices range from $133,000 to $5,500,000.

Prices as low as $3,000,000 per MIP !

In 1964 a nice house cost about $6,000

Today zSeries pricing is less than $1000 per MIP

System/360 was introduced in 1964. z/OS, its successor, is the result of 40 years of constant innovation and refinement. From the System/360 Model 40 to the zSeries 990, and from the beginnings of OS/360 to z/OS, new capabilities and technologies have been added while protecting your investment in existing applications.

EBCDIC

The IBM S/360 through to the latest zSeries machines use the Extended Binary Coded Decimal Interchange character set for most purposes

This was developed before ASCII and is also an 8 bit character set z/OS Web Server stores ASCII data as most browsers run on PCs which expect ASCII data

Mainframe is a computing system that businesses use to host the commercial databases, transaction servers, and applications that require a greater degree of security and availability than is commonly found on smaller-scale machines.

The power of a mainframe provides computing speed and capacity, enabling it to perform high volumes of processing.

The mainframe can process a mixed workload of jobs from different time zones and of different types.

Today, computer manufacturers dont always use theterm mainframe to refer to mainframes. Instead, most have taken to calling anycommercial-use computerlarge or smalla server, with the mainframe simply beingthe largest type of server in use today. IBM, for example, now refers to its mainframes aszSeries servers. We use the term mainframe in this textbook to refer to computers thatcan support dozens of applications and input/output devices to simultaneously servethousands of users.

The presence of a mainframe often implies a centralized form of computing, rather than adistributed form of computing. Having data centralized in a single mainframe repositorysaves customers from having to manage updates to more than one copy of their businessdata, and increases the likelihood that the data is current.

What is a mainframe?

Compatibility with operating systems, applications and data, centralized control of resources, HW and operating systems share disk access, A STYLE of operation, thousands of simultaneous I/O operations, clustering technologies and additional data and resource sharing capabilities

Roles in the mainframe world:

System administrators perform more of the day-to-day tasksrelated to maintaining the critical business data that resides on the mainframe, while the system programmer focuses on maintaining the system itself.

Examples of system administrators include database administrators andsecurity administrators.

While system programmer expertise lies mainly in the mainframe hardware and softwareareas, system administrators are more likely to have experience with the applications.

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The application designer and application programmer (or developer) design, build, test,and deliver mainframe applications for the companys end users and customers. Based onrequirements gathered from business analysts and end users, the designer creates a designspecification from which the programmer constructs an application. The process includesmany iterations of code changes and compiles, application builds, and unit testing.

The system operator monitors and controls the operation of the mainframe hardware andsoftware. The operator starts and stops system tasks, monitors the system consoles forunusual conditions, and works with the system programming and production control staffto ensure the health and normal operation of the systems.

The production control analyst is responsible for ensuring that batch workloads run tocompletion--without error or delay.

Disk S toragedatabases

Tape StorageSequential

data sets

P artners and clients exchange

informat ion Reports

Backups

Data update

Reports

Statis tics, summaries, except ions

ResidenceM ain o ffice

Branch o ffices Account balances bills, etc

Processingreports

MainframeP rocessing batch jobs

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55Reports

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1010

11

88

66

33

CR ED I T CA RD

12 34 56 78 901 21 234 56 78 90 12V A LID FR O M G OO D TH R UX X / X X/ X X X X /X X / X X

P A U L F I S C H E R

X X / X X /X X X X /X X / X X

P A U L F IS C H E R

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99

SystemOperator

Product ionControl

Typical batch use

Notes:

A batch job is submitted on the computer,reads and processes data in bulk, and produces output. A batch job can last for hours.

While batch processing is possible on distributed systems, it is not as commonplace as onmainframes because distributed systems often lack:

Sufficient data storage Available processor capacity or cycles Sysplex-wide management of system resources and job scheduling.

Mainframes serve a vast number of online transaction processing (OLTP) systems.

These are often mission-critical applications that businesses depend on for their corefunctions. Some industry uses of online systems:

Banks ATMs, teller systems for customer service Insurance Agent systems for policy management and claims processing Travel and transport Airline reservation systems Manufacturing Inventory control, production scheduling Government Tax processing, license issuance and management.

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Typical batch use

Consider the following elements at work in the scheduled batch process:

1. At night, many batch jobs executing programs and utilities are processed. These jobsconsolidate the results of the online transactions executed during the day.

2. The batch jobs generate reports of business statistics.

3. Backups of critical files and databases are made before and after the batch window.

4. Reports with business statistics are sent to a specific area for analysis during thefollowing day.

5. Reports with exceptions are sent to the branch offices.

6. Monthly account balance reports are generated and sent to all bank customers.

7. Reports with processing summary are sent to the partner credit card company.

8. A credit card transaction report is received from the partner company.

9. In the production control department, the operations area is monitoring the messageson the system console and the execution of the jobs.

10. Jobs and transactions are reading or updating the database (the same database used byonline transactions) and many files are written to tape.

Disk storage

controllerStores

database f iles

queries and

updates

A ccount act ivi ties

O ff iceautom ation

system s

MainframeAccessesdatabase

Requests

ATMs

Branchoffices

Business analysts Inventory contro l

Branch of fice autom ation system s

SNA or TCP/IPnetwork

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66

3322

4411

Central office

Typical online use

Notes: Common online transactions using a mainframe:

1. A customer uses an ATM, which presents a user-friendly interface for various functions: Withdrawal, query account balance, deposit, transfer, or cash advance froma credit card account.

2. Elsewhere in the same private network, a bank employee in a branch office performsoperations such as consulting, fund applications, and money ordering.

3. At the banks central office, business analysts tune transactions for improved performance. Other staff use specialized online systems for office automation to perform customer relationship management, budget planning, and stock control.

4. All requests directed to the mainframe computer for processing.

5. Programs running on the mainframe computer perform updates and inquires to thedatabase management system (for example, DB2).

6. Specialized disk storage systems store the database files.

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ESCON/FICON

IBM System z Parallel Sysplex

Coupling Facility

SYSPLEX Timer

Shared Data

Notes: The purpose of the mainframe* RAS strategy is to enable delivery to our customers of servers which are capable of continuous reliable operation (CRO). The two elements of CRO, continuous and reliable, require the server to run the customers operation without interruption caused by errors, maintenance, or change in server hardware or Licensed Internal Code (LIC), while ensuring error-free execution and data integrity. The seven building blocks of this strategy, which are intended to support the drive to CRO, are error prevention, error detection, recovery, problem determination, service structure, change management, and measurement and analysis.

Sysplex: Is a collection of z/OS Systems that cooperate, using certain hardware, software and microcode to process workloads providing higher availability, easier systems management and improve growth over a conventional computer system of comparable processing power. Parallel and clustered systems initially found in numerically intensive markets have gained increasing acceptance in commercial segments as well. The architectural elements of these systems span a broad spectrum that includes massively parallel processors that focus on high performance for numerically intensive workloads, and cluster operating systems that deliver high system availability.

The zSeries cluster (parallel system complex, or Parallel Sysplex) contains innovative multisystem data-sharing technology, allowing direct, concurrent read/write access to shared data from all processing nodes in the parallel configuration, without sacrificing performance or data integrity. Each node is able to concurrently cache shared data in local processor memory through hardware-assisted cluster-wide serialization and coherency controls. This in turn enables work requests associated with a single workload, such as business transactions or database queries, to be dynamically distributed for parallel execution on nodes in the sysplex cluster, based on available processor capacity. Through this state-of-the-art cluster technology, the power of multiple z/Series systems can be harnessed to work in concert on common workloads, taking the commercial strengths of the z/OS platform to improved levels of competitive price/performance, scalable growth, and continuous availability.

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Prior to Parallel Sysplex, S/390 and today zSeries customers had been forced to contain the capacity requirements of a workload within the technology limits imposed by the size of the largest single symmetric multiprocessor system available. Workload growth beyond these limits required splitting the workload and re partitioning the database between the nodes: a complex, resource-intensive process not supportive of customer business objectives.

What a Sysplex can do for YOU.

It will address any of the following types of work

Large business problems that involve hundreds of end users, or deal with volumes of work that can be counted in millions of transactions per day.

Work that consists of small work units, such as online transactions, or large work units that can be subdivided into smaller work units, such as queries.

Concurrent applications on different systems that need to directly access and update a single database without jeopardizing data integrity and security.

Provides reduced cost through Cost effective processor technology

IBM software licensing charges in Parallel Sysplex

Continued use of large-system data processing skills without re-education

Protection of z/OS application investments

The ability to manage a large number of systems more easily than other comparably performing multisystem environments

Platform for continuous availability so that applications can be available 24 hours a day, 7 days a week, 365 days a year

Ability to do more work

Greater capacity

Improved ability to manage response time

Platform for further capacity and response time advances

Greater flexibility Ability to mix levels of hardware and software

Ability to dynamically add systems

An easy path for incremental growth

Varied platforms for applications, including parallel, open, and client/server

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Intelligent Workload Manager The idea of Workload Manager is to make a contract between the installation (end user) and the operating system. The installation classifies the work running on the z/OS operating system in distinct service classes and defines goals for them which express the expectation how the work should perform. WLM uses these goal definitions to manage the work across all systems of a parallel sysplex environment.

Coupling facility Authorized applications, such as subsystems and z/OS components in the sysplex, use the Coupling Facility services to cache data, share queues and status, and access sysplex lock structures in order to implement high-performance data sharing and rapid recovery from failures. The subsystems and components transparently provide the data sharing and recovery benefits to their applications.

Some IBM data management systems that use the Coupling Facility include database managers and a data access method:

Information Management System Database (IMS DB) Database 2 (DB2) Virtual Storage Access Method

*LPAR: Logical Partitions are, in practice, equivalent to separate mainframes images. Each LPAR runs its own operating system. This can be any mainframe operating system.

LPAR

Notes: LPAR: Logical Partitions are, in practice, equivalent to separate mainframes images. Each LPAR runs its own operating system. This can be any mainframe operating system.

LPAR

System administrators assign:

Memory

Processors

CHPIDs either dedicated or shared

This is done partly in the IOCDS and partly in a system profile on the Support Element (SE) in the CEC. This is normally updated through the HMC.

Changing the system profile and IOCDS will usually require a power-on reset (POR) but some changes are dynamicCharacteristics of LPARs

LPARs are the equivalent of a separate mainframe for most practical purposes

Each LPAR runs its own operating system Devices can be shared across several LPARs Processors can be dedicated or shared When shared each LPAR is assigned a number of logical processors (up to the maximum number

of physical processors) and a weighting

Each LPAR is independent

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Unit 2

z/OS

The most widely used mainframe operating system

64-bit operating system

Ideally suited for processing large workloads for many concurrent users Designed for:

Serving 1000s of users concurrently I/O intensive computing Processing very large workloads Running mission critical applications securely

What is z/OS?

Notes: The operating system we discuss in this course is z/OS, the most widely used of all mainframe operating systems. z/OS is designed to offer a stable, secure, and continuously available environment for applications running on the mainframe.

To understand how and why z/OS functions as it does, it is important to understand the environment in which it functions. The special features that make z/OS unique reflect the computer environments that z/OS manages.

z/OS gets work done by dividing it into pieces and giving portions of the job to various system components and subsystems that function interdependently. At any point in time, one component or another gets control of the processor, makes its contribution, and then passes control along to a user program or another component.

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S ys t em C on s ole( ha rd wa re )

M a s ter C on s ole( z /O S )

O p er at or C on s ole( z /O S )

M a in fr a m e co m p u te r(C P U , p ro ce ss o r

s t o ra g e )

z / O S r u n n in g h e r e .. .

D is k s tor ag e (D AS D vo lu m e s)

DA S D c o n tr o l le r

Tap e d r iv e

Ta pe c ar tr idge s

. .. D i r e c t o r l in k s m a in fr a m e s w it h D A S D c o n t r o l le r s

Hardware resources managed by z/OS

Notes: Mainframe hardware consists of processors and a multitude of peripheral devices such as disk drives (called direct access storage devices or DASD), magnetic tape drives, and various types of user consoles. Tape and DASD are used for system functions and by user programs executed by z/OS.

Not shown here, for example, are the hardware control units, such as the director, which connect the mainframe to the other tape drives, DASD devices, and consoles.

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16 EB

64-bit addresing(z/OS)

The Bar 2GB

31-bit addresing(MVS/XA)

16 MBThe Line 24-bit addresing

(MVS)

Virtual storage is an i llusion created through z/OS management of real storage and auxiliary storage through tables.

The running portions of a program are kept in real storage; the rest is kept in auxiliary storage

Range of addressable virtual storage available to a user or program or the operating system is an address space

Each user or separately running program is represented by an address space (each user gets a limited amount of private storage)

Virtual storage and address space concept

Notes: Virtual storage means that each running program can assume it has access to all of thereal storage defined by the architectures addressing scheme. The only limit is the number of bits in a storage address.

To allow each user to act as though this much storage really exists in the computer system, z/OS keeps only the active portions of each program in real storage. z/OS keeps the rest of the code and data in special files on auxiliary storage, which usually consists of a number of high-speed direct access storage devices (DASDs).

An address space is the area of contiguous virtual addresses available for executing instructions and storing data. The range of virtualaddresses in an address space starts at zero and can extend to the highest address permitted by the operating system architecture.

z/OS provides each user with a unique address space and maintains the distinction between the programs and data belonging to each address space.

With the release of zSeries mainframes in 2000, IBM extended the addressability of the architecture to 64 bits. With 64-bit addressing, the potential size of a z/OS addressspace expands to a size so vast that we need new terms to describe it. Each address space,called a 64-bit address space, is 16 exabytes (EB) in size; an exabyte is slightly more thanone billion gigabytes. The new address space has logically 264 addresses. It is 8 billiontimes the size of the former 2 GB address space. The number is 16 with 18 zeros after it:16,000,000,000,000,000,000 bytes, or 16 EB (see the slide).

We say that the potential size is 16 exabytes because z/OS, by default, continues to createaddress spaces with a size of 2 GB. The address space exceeds this limit only if a program running in it allocates virtual storage above the 2 GB address. If so, the z/OS operating system increases the storage available to the user from 2 GB to 16 EB.

The 16 MB address became the dividing point between the two previous architectures (the 24-bit addressability introduced with MVS/370 and the 31-bit addressing introduced in the operating system MVS Extended

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that separates the virtual storage e user private area is called the bar.

ge addresses as 24 bits in length, providing addressability for up to

70-XA extended the addressability of the architecture to 31 bits, for up to 2GB of virtual

2000: z/Architecture extended the addressability to 64 bits, for up to 16EB of virtual storage.

ow virtual storage works:

Architecture or MVS/XA), and is commonly called the line. The area area below the 2 GB address from th

Brief history of z/OS addressability

System/370 defined stora16MB of virtual storage.

System/3storage.

H

naled and the

mic Address Translation (DAT) page of information

ress space (that is, all addresses

54000 can exist more than once, because each virtual address

is signaled toz/OS and the perating system brings the required instructions and data into real storage.

Virtual storage is divided into 1-megabyte segments composed of 4-kilobyte pages Transfer of pages between auxiliary storage and real storage is called paging When a requested page is not in real storage, an interruption (called a page fault) is sigsystem brings it into real storage z/OS uses segment and page tables to keep track of pages Addresses are translated dynamically, a process called DynaFrames and slots are repositories for aA frame is a 4K piece of real storage

A slot is a 4K record in a page data set

An address is an identifier of a required piece of information, but not a description of where in real storage that piece of information is. This allows the size of an addavailable to a program) to exceed the amount of real storage available.

All real storage references are made in terms of virtual storage addresses.

A hardware mechanism is used to map the virtual storage address to a physical location in real storage. As shown on the slide, the virtual address 102maps to a different address in real storage.

When a requested address is not in real storage, a hardware interruptiono

z/OS and its related subsystems require address spaces of their own to provide a functioning operating system:

System address spaces are started after initialization of the master scheduler. These address spaces perform functions for all the other types of address spaces that start in z/OS.

Subsystem address spaces for major system functions and middleware products such as DB2, CICS, and IMS.

TSO/E address spaces are created for every user who logs on to z/OS

Address spaces for every batch job that runs on z/OS.

z/OS address spaces

Notes: We wont attempt to list all of the z/OS program products in this course (hundreds exist); some common choices include:

A security system z/OS provides a framework for customers to add security through the addition of a security management product (IBMs program product is Resource Access Control Facility or RACF). Non-IBM security system program products are also available.

Compilers z/OS includes an assembler and a C compiler. Other compilers, such as the COBOL compiler, are offered as separate products.

A relational database, such as DB2 Other types of database products, such as hierarchical databases, are also available.

Transaction processing facilities IBM offers several, including:

Customer Information Control System (CICS)

Information Management System (IMS)

WebSphere

A sort program

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Fast, efficient sorting of large amounts of data is highly desirable in batch processing.

IBM and other vendors offer sophisticated sorting products.

A large variety of utility programs For example, the System Display and Search Facility (SDSF) program that we use extensively in this course to view output from batch jobs is a program product. Not every installation purchases SDSF; alternative products available.

A large number of other products are available from various independent software vendors (commonly called ISVs in the industry).

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Unit 3

Interactive facilities of z/OS:

TSO/E and ISPF

Enter LOGON parameters below: RACF LOGON parameters:

Userid ===> ZPROF

Password ===> New Password ===>

Procedure ===> IKJACCNT Group Ident ===>

Acct Nmb r ===> ACCNT#

Size ===> 860000

Perform ===>

Command ===>

Enter an 'S' before each option desired below: -Nomail -Nonotice -Reconnect -OIDcard

PF1/PF13 ==> Help PF3/PF15 ==> Logoff PA1 ==> Attention PA2 ==> ReshowYou may request sp ecific help information by entering a '?' in any entry field

TSO/E

Allow s users to logon to z/OS and use a limited set of basic commands. This is sometimes called using TSO in its native mode.

ISPF

Provides a menu system for accessing many of the most commonly used z/OS functions.

TSO/E logon screen

How do we interact with z/OS?

Notes: z/OS provides a number of facilities to allow users to interact directly with the operating system. In this education module, well look at each facility briefly. At the end, well work through some simple exercises to give the student some hands-on experience with z/OS.

TSO allows users to log on to z/OS and access a limited set of basic TSO commands, which are available as part of the core operating system. Interacting with z/OS in this way is called using TSO in its native mode.

ISPF is an application that runs on z/OS and provides a menu-style shell for TSO users. ISPF menus list the functions that are most frequently needed by online users. ISPF is what many people use exclusively to perform work on z/OS.

The z/OS UNIX shell and utilities allow users to write and invoke shell scripts and utilities, and use the shell programming language.

Hands-on exercises are provided at the end of the chapter to help students develop their understanding of these important facilities.

In a z/OS system, each user is granted a user ID and a password authorized for TSO logon. Logging on to TSO requires a 3270 display device or, more commonly, a TN3270 emulator running on a PC. During TSO logon, the system displays the TSO logon screen on the users 3270 display device or TN3270 emulator. The logon screen serves the same purpose as a Windows logon panel.

Logon proc allocates the data sets youll need, the resources you can access (RACF), the region size for your address space.

Use reconnect if you lose your connection.

Notice the PF Keys? Many of the screen capture examples used in this textbook show program function (PF) key settings. Because it is common practice for z/OS sites to customize the PF key assignments to suit their needs, the key assignments shown in this textbook might not match the PF key settings in use at your site.

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Well look at the PF key assignments used in this course in a slide coming up.

Most z/OS sites prefer to have the TSO user session automatically switch to the ISPF interface after TSO logon. This section, however, briefly discusses the limited set of basic TSO commands available independent of other complimentary programs, such as ISPF. Using TSO in this way is called using TSO in its native mode.

Native TSO is similar to the interface offered by the native DOS prompt. TSO also includes a very basic line mode editor, in contrast to the full screen editor offered by ISPF.

The next slide shows an example of a user entering commands at the READY prompt to sort data.

After logging on to TSO, users typically access the ISPF menu. In fact, many use ISPF exclusively for performing work on z/OS. ISPF is a full panel application navigated by keyboard. ISPF includes a text editor and browser, and functions for locating and listing files and performing other utility functions. ISPF menus list the functions that are most frequently needed by online users.

To access ISPF under TSO, the user enters a command from the READY prompt to display the ISPF Primary Option Menu. You can access online help from any of the ISPF panels (press the PF1 key)

ISPF includes a text editor and browser, and functions for locating files and performing other utility functions.

Action Bar

Panel Options

Command Line

Function Keys

D ynamic StatusArea

Menu Utilities Compilers Options Status Help --------------------------------------------------------------------------- ISPF Primary Option Menu 0 Settings Terminal and user parameters User ID . : AUES100 1 View Display source data or listings Time. . . : 16:14 2 Edit Create or change source data Terminal. : 3278 3 Utilities Perform utility functions Screen. . : 1 4 Foreground Interactive language processing Language. : ENGLISH 5 Batch Submit job for language processing Appl ID . : ISR 6 Command Enter TSO or Workstation commands TSO logon : LOGON 7 Dialog Test Perform dialog testing TSO prefix: AUES100 8 LM Facility Library administrator functions System ID : SYS1 9 IBM Products IBM program development products MVS acct. : ACCNT# 10 SCLM SW Configuration Library Manager Release . : ISPF 5.2 11 Workplace ISPF Object/Action Workplace S SDSF System Display and Search Facility Enter X to Terminate using log/list defaults

Option ===> F1=Help F2=Split F3=Exit F7=Backward F8=Forward F9=Swap F10=Actions F12=Cancel

General structure of ISPF panels

Notes: Option zero (O) allows you to change ISPF settings. For example, the command line for your ISPF session might appear at the bottom of the display, while your instructors ISPF command line might appear at the top. This is a personal preference, but traditional usage places it at the top of the panel. If you want your command line to appear at the top of the panel, do the following:

1. Go to the ISPF primary option menu. 2. Select option 0 to display the Settings menu, as shown in Figure 3-17 on page 3-22. 3. In the list of Options, remove the / on the line that says Command line at bottom. Use the Tab

or New line key to move the cursor.

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Option 1 VIEW

Notes:

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Browsing data display

Option 1 VIEW

Notes:

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C:\AUTOEXEC.BAT

Option 2 E D I T

Notes:

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Option 3 UTILITIES

Notes:

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30

Unit 4

Working with data sets

What is a data set ? A data set is a collection of logically related data records stored on one disk storage volume or a set of volumes.

Dataset Naming

Using a data set To use a data set, you f irst allocate it.

Access Method Defines the technique used to store and retrieve data.

Data Sets

Notes: A data set is a collection of logically related data; it can be a source program, a library of programs, or a file of data records used by a processing program. Data records are the basic unit of information used by a processing program.

z/OS data sets are allocated in contiguous extents on a disk to enhance performance.

Users must define the amount of space to be allocated for a data set (before it is used). A data set may occupy more than one extent and extents may be added dynamically.

Almost all z/OS data processing is record-oriented. Byte stream files are not present in traditional processing, although they are a standard part of z/OS UNIX. z/OS records

(and physical blocks) are in one of several well-defined formats. Most data sets have DCB attributes that include the record format (RECFMF, FB, V, VB, U), the maximum logical record length (LRECL), and the maximum block size (BLKSIZE).

A data set can be:

a source program a library of macros a file of data records used by a processing program.

You can print a data set or display it on a terminal. The logical record is the basic unit of information used by a program running on z/OS.

Data set naming convention

Unique name, maximum 44 characters

Maximum of 22 name segments: level qualifier. Level qualifiers are separated by '.'

Each level qualifier: From 1 up to 8 characters, the first must be alphabetical (A-Z) or special (@ # $), the 7 remaining: alphabetical, national, numeric (0-9) or hyphen (-), upper case only. Example: MYID.JCL.FILE2 HLQ: MYID 3 qualifiers

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Member name of partitioned data set: 8 bytes long, first byte: alphabetical (A-Z) or special (@ # $), the 7 remaining: alphabetical, special, numeric (0-9)

When you allocate a new data set (or when the operating system does), you must give the data set a unique name.

A data set name can be one name segment, or a series of joined name segments. Each name segment represents a level of qualification. For example, the data set name VERA.LUZ.DATA is composed of three name segments. The first name on the left is called the high-level qualifier (HLQ), the last name on the right is the lowest-level qualifier (LLQ).

Segments or qualifiers are limited to eight characters, the first of which must be alphabetic (A to Z) or special (# @ $). The remaining seven characters are either alphabetic, numeric (0 - 9), special, a hyphen (-). Name segments are separated by a period (.).

To use a data set, you first allocate it (establish a link to it), then access the data usingmacros for the access method that you have chosen.

The allocation of a data set means either or both of two things: To set aside (create) space for a new data set on a disk. To establish a logical link between a job step and any data set.

You can specify the amount of space required in blocks, records, tracks, or cylinders.

When creating a DASD data set, you specify the amount of space needed explicitly (by using the SPACE parameter), or implicitly (by using the information available in a data class).

Various ways to allocate a data set:

ISPF data set panel, option 3.2 Access Method Services TSO ALLOCATE command job control language (JCL)

Access method

Defines the technique used to store and retrieve data.

Includes system-provided programs and utilities to define and process data sets.

VSAM Commonly used access methods DASD: Use and terminology Direct Access Storage Device (DASD) is another name for a disk drive. DASD volumes are used for storing data and executable programs.

Data sets in a z/OS system are organized on DASD volumes. A disk drive contains cylinders Cylinders contain tracks Tracks contain data records.

Record and block descriptors words are each 4 bytes long

Data set record formats

r e c o r d re c o r d re c o r d r e c o r dFF ixe d r e c o r d s .

b lo c k b lo c k

r e c o rdre c o r d r e c o r dr e c o r d r e c o r d r e c o r dF BF ixe d b lo c k e d r ec o r ds . B L K S I Z E = n * L RE C L

b lo c k

re c o r d

b lo c k

re c o r d r e c o r d

r e c o r d re c o r d r e c o r d re c o r dre c o rd

B D W

V

V B

R D WV a r ia b le re c o rd s .

V a r ia b le b lo c k e d re c o r d s. B L K S IZ E > = 4 + n * la r ge s t L R E C L

r e c o r d re c o r d re c o r d r e c o r dFF ixe d r e c o r d s .

r e c o r d re c o r d re c o r d r e c o r dFF ixe d r e c o r d s .

b lo c k b lo c k

r e c o rdre c o r d r e c o r dr e c o r d r e c o r d r e c o r dF BF ixe d b lo c k e d r ec o r ds . B L K S I Z E = n * L RE C L

b lo c k b lo c k

r e c o rdre c o r d r e c o r dr e c o r d r e c o r d r e c o r dF BF ixe d b lo c k e d r ec o r ds . B L K S I Z E = n * L RE C L

b lo c k

re c o r d

b lo c k

re c o r d r e c o r d

r e c o r d re c o r d r e c o r d re c o r dre c o rd

B D W

V

V B

R D WV a r ia b le re c o rd s .

V a r ia b le b lo c k e d re c o r d s. B L K S IZ E > = 4 + n * la r ge s t L R E C L

b lo c k

re c o r d

b lo c k

re c o r d r e c o r d

r e c o r d re c o r d r e c o r d re c o r dre c o rd

B D W

V

V B

R D WV a r ia b le re c o rd s .

V a r ia b le b lo c k e d re c o r d s. B L K S IZ E > = 4 + n * la r ge s t L R E C L

Notes: Traditional z/OS data sets are record oriented. In normal usage, there are no byte stream files such as are found in PC and UNIX systems. (z/OS UNIX has byte stream files, and byte stream functions exist in other specialized areas. These are not considered to be traditional data sets.)

In z/OS, there are no new line (NL) or carriage return and line feed (CR+LF) characters to denote the end of a record. Records are either fixed length or variable length in a given data set. When editing a data set with ISPF, for example, each line is a record.

Traditional z/OS data sets have one of five record formats, as shown on the slide. We must stress the difference between a block and a record. In this discussion, a block is what is written on disk, while a record is a logical entity. F - Fixed This means that one physical block on disk is one logical record and all the blocks/records are the same size. This format is seldom used.

FB - Fixed Blocked This means that several logical records are combined into one physical block. This can provide efficient space utilization and operation. This format is commonly used for fixed-length records.

V - Variable This format has one logical record as one physical block. The application is required to insert a four-byte Record Descriptor Word (RDW) at the beginning of the record. The RDW contains the length of the record plus the four bytes for the

RDW. This format is seldom used.

VB - Variable Blocked This format places several variable-length logical records (each with an RDW) in one physical block. The software must place an additional Block Descriptor Word (BDW) at the beginning of the block, containing the total length of the block. U - Undefined This format consists of variable-length physical records/blocks with no predefined structure. Although this format may appear attractive for many unusual applications, it is normally used only for executable modules.

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Sequential

Partitioned

Types of data sets

Notes: The simplest data structure in a z/OS system is a sequential data set. It consists of one or more records that are stored in physical order and processed in sequence. New records are appended to the end of the data set.

An example of a sequential data sets might be an output data set for a line printer or a deck of punch cards.

A z/OS user defines sequential data sets through job control language (JCL) with a data set organization of PS (DSORG=PS), which stands for physical sequential. In other words, the records in the data set are physically arranged one after another.

A partitioned data set adds a layer of organization to the simple structure of sequential data sets. A PDS is a collection of sequential data sets, called members. Each member is like a sequential data set and has a simple name, which can be up to eight characters long.

A PDS also contains a directory. The directory contains an entry for each member in the PDS with a reference (or pointer) to the member. Member names are listed alphabetically in the directory, but members themselves can appear in any order in the library. The directory allows the system to retrieve a particular member in the data set.

A partitioned data set is commonly referred to as a library. A PDSE is a partitioned data set extended. It consists of a directory and zero or more members, just like a PDS. It can be created with JCL, TSO/E, and ISPF, just like a PDS, and can be processed with the same access methods. PDSE data sets are stored only on DASD, not tape.

PDS data sets:

Simple and efficient way to organize related groups of sequential files.

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PDSE data sets:

Similar to a PDS, but advantages include: Space reclaimed automatically when a member is deleted, flexible size, can be shared, faster directory searches

A PDS data set offers a simple and efficient way to organize related groups of sequential files. A PDS has the following advantages for z/OS users:

Grouping of related data sets under a single name makes z/OS data management easier. Files stored as members of a PDS can be processed either individually or all the members can be processed as a unit.

Because the space allocated for z/OS data sets always starts at a track boundary on disk, using a PDS is a way to store more than one small data set on a track. This saves you disk space if you have many data sets that are much smaller than a track. A track is 56,664 bytes for 3390 disk device.

Members of a PDS can be used as sequential data sets, and they can be appended (or concatenated) to sequential data sets.

Multiple PDS data sets can be concatenated to form large libraries. PDS data sets are easy to create with JCL or ISPF; they are easy to manipulate with ISPF utilities

or TSO commands.

However, some aspects of the PDS design affect both performance and the efficient use of disk storage, as follows: Wasted space. When a member in a PDS is replaced, the new data area is written to a new section within the storage allocated to the PDS. When a member is deleted, its pointer is deleted too, so there is no mechanism to reuse its space.

Limited directory size. The size of a PDS directory is set at allocation time. As the data set grows, it can acquire more space in units of the amount you specified as its secondary space. These extra units are called secondary extents. However, you can only store a fixed number of member entries in the PDS directory because its size is fixed when the data set is allocated. If you need to store more entries than there is space for, you have to allocate a new PDS with more directory blocks and copy the members from the old data set into it.

Lengthy directory searches. Entries are searched sequentially in alphabetical order. If the directory is very large and the members small, it might take longer to search the directory than to retrieve the member when its location is found.

In many ways, a PDSE is similar to a PDS. Each member name can be eight bytes long.

For accessing a PDS directory or member, most PDSE interfaces are indistinguishable from PDS interfaces. Both PDS and PDSE data sets are processed using the same access methods. However, PDSE data sets have a different internal format, which gives them increased usability. You can use a PDSE in place of a PDS to store data, or to store programs in the form of program objects. A program object is similar to a load module in a PDS. A load module cannot reside in a PDSE and be used as a load module. One PDSE cannot contain a mixture of program objects and data members.

PDSE data sets have several features that can improve user productivity and system performance. The main advantage of using a PDSE over a PDS is that a PDSE automatically reuses space within the data set without the need for anyone to periodically run a utility to reorganize it.

Also, the size of a PDS directory is fixed regardless of the number of members in it, while the size of a PDSE directory is flexible and expands to fit the members stored in it.

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Further, the system reclaims space automatically whenever a member is deleted or replaced, and returns it to the pool of space available for allocation to other members of the same PDSE. The space can be reused without having to do an IEBCOPY compress.

In a z/OS system, data can be stored on a direct access storage device (DASD), magnetic tape volume, or optical media. The term DASD applies to disks or simulated equivalents of disks. All types of data sets can be stored on DASD, but only sequential data sets can be stored on magnetic tape. We discuss the types of data sets later in this module.

When a member in a PDS is replaced, the new data area is written to a new section within the storage allocated to the PDS. When a member is deleted, its pointer is deleted too, so there is no mechanism to reuse its space. This wasted space is often called gas and must be periodically removed by reorganizing the PDS, for example, by using the utility IEBCOPY to compress it.

Catalog Structure

Locating a dataset in MVS - Catalogs and VTOCs

Notes: Catalog

A catalog describes data set attributes and indicates the volumes on which a data set is located. Data sets can be cataloged, uncataloged, or recataloged. All system-managed DASD data sets are cataloged automatically in a catalog. Cataloging of data sets on magnetic tape is not required but usually it simplifies users jobs. All data sets can be cataloged in a catalog.

In z/OS, the master catalog and user catalogs store the locations of data sets by name. This means that data set names must be unique. Both disk and tape data sets can be cataloged.

To find a data set that you have requested, z/OS must know three pieces of information:

Data set name Volume name Unit (the volume device type, such as a 3390 disk or 3590 tape)

You can specify all three values on ISPF panels or in JCL. However, the unit device type and the volume are often not relevant to an end user or application program.

Catalog Structure

A z/OS system always has at least one master catalog. If a z/OS system has a single catalog, this catalog would be the master catalog and the location entries for all data sets would be stored in it. A single catalog, however, would be neither efficient nor flexible, so a typically z/OS system uses a master catalog and numerous user catalogs connected to it as shown on the slide. A user catalog stores the name and location of a data set (dsn/volume/unit). The master catalog usually stores only a data set HLQ with the name of the user catalog, which contains the location of all data sets prefixed by this HLQ. The HLQ is called an alias.

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The VTOC lists the data sets that reside on its volume, along with information about the location and size of each data set, and other data set attributes. A standard z/OS utility program, ICKDSF, is used to create the label and VTOC.

When a disk volume is initialized with ICKDSF, the owner can specify the location and size of the VTOC. The size can be quite variable, ranging from a few tracks to perhaps 100 tracks, depending on the expected use of the volume. More data sets on the disk volume require more space in the VTOC.

The VTOC also has entries for all the free space on the volume. Allocating space for a data set (described later) causes system routines to examine the free space records, update them, and create a new VTOC entry. Data sets are always an integral number of tracks (or cylinders) and start at the beginning of a track (or cylinder).

Data Facility Subsystem Managed Storage (DFSMS)

Notes: In a z/OS system, data management involves allocation, placement, monitoring, migration, backup, recall, recovery, and deletion. These activities can be done either manually or through the use of automated processes. When data management is automated, the operating system determines object placement, and automatically manages object backup, movement, space, and security. A typical z/OS production system includes both manual and automated processes for managing data sets.

Data management includes these main tasks:

Setting aside (allocating) space on DASD volumes Automatically retrieving cataloged data sets by name Mounting magnetic tape volumes in the drive Establishing a logical connection between the application program and the medium Controlling access to data Transferring data between the application program and the medium

DFSMS performs the essential data, storage, program, and device management functions of the system. DFSMS is a set of products, and one of these products, DSFMSdfp, is required for running z/OS. DFSMS, together with hardware products and installation-specific settings for data and resource management, provides system-managed storage in a z/OS environment.

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40

The heart of DFSMS is the Storage Management Subsystem (SMS). Using SMS, the system programmer or storage administrator defines policies that automate the management of storage and hardware devices. These policies describe data allocation characteristics, performance and availability goals, backup and retention requirements, and storage requirements for the system. SMS governs these policies for the system and the Interactive Storage Management Facility (ISMF) provides the user interface for defining and maintaining the policies.

The data sets allocated through SMS are called system-managed data sets or SMS-managed data sets.

VSAM is Virtual Storage Access Method

VSAM provides more complex functions than other disk access methods

VSAM record formats: Key Sequence Data Set (KSDS)

Entry Sequence Data Set (ESDS)

Relative Record Data Set (RRDS)

Linear Data Set (LDS)

VSAM

Notes: The term Virtual Storage Access Method (VSAM) applies to both a data set type and the access method used to manage various user data types.

As an access method, VSAM provides much more complex functions than other disk access methods. VSAM keeps disk records in a unique format that is not understandable by other access methods. VSAM is primarily for applications. It is not used for source programs, JCL, or executable modules. VSAM files cannot be routinely displayed or edited with ISPF.

You can use VSAM to organize records into four types of data sets: key-sequenced, entry-sequenced, linear, or relative record. The primary difference among these types of data sets is the way their records are stored and accessed.

VSAM data sets are briefly described as follows:

Key Sequence Data Set (KSDS)

This is the most common use for VSAM. Each record has one or more key fields and a record can be retrieved (or inserted) by key value. This provides random access to data. Records are of variable length.

Entry Sequence Data Set (ESDS)

This form of VSAM keeps records in sequential order. Records can be accessed sequentially. It is used by IMS, DB2, and z/OS UNIX.

Relative Record Data Set (RRDS)

This VSAM format allows retrieval of records by number; record 1, record 2, and so forth. This provides random access and assumes the application program has a way to derive the desired record numbers.

Linear Data Set (LDS)

This is, in effect, a byte-stream data set and is the only form of a byte-stream data set in traditional z/OS files (as opposed to z/OS UNIX files). A number of z/OS system functions use this format heavily, but it is rarely used by application programs.

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Unit 5

Using Job Control Language (JCL), System

Display and Search Facility (SDSF) and JES

.

Job control language (JCL) tells the system w hat program to execute and provides a description of program inputs and outputs.

There are three basic JCL statements: JOB, EXEC e DD

Exemplo

JCL

Notes: The details of JCL can be complicated but the general concepts are quite simple. Also, a small subset of JCL accounts for at least 90% of what is actually used. This chapter discusses selected JCL options.

While application programmers need some knowledge of JCL, the production control analyst responsible must be highly proficient with JCL, to create, monitor, correct and re-run the companys daily batch workload.

There are three basic JCL statements:

JOB Provides a name to the system for this batch workload. It can optionally include accounting information and a few job-wide parameters.

EXEC Provides the name of a program to execute. There can be multiple EXEC statements in a job. Each EXEC statement within the same job is a job step. DD The Data Definition provides inputs and outputs to the execution program on the EXEC statement. This statement links a data set or other I/O device or function to a DDNAME coded in the program. DD statements are associated with a particular job step.

Each JCL DD statement is equivalent to the TSO ALLOCATE command. Both are used to associate a z/OS data set with a ddname, which is recognized by the program as an input or output. The difference in method of execution is that TSO executes the sort in the foreground while JCL is used to execute the sort in the background, or batch.

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In the example:

JOB statement JOB JCL statement //MYJOB JOB 1 is a job card with name MYJOB. The 1 is a job card accounting field that can be subject to system exits that might be used for charging system users. Some common JOB card operands that could be included are:

REGION= Value requesting specific memory resources allocated to this job

NOTIFY= Message can be sent to a TSO user ID, following job completion

USER= Job will assume the authority of the user ID specified

TYPRUN= It is possible to submit the job on HOLD, to be released later

CLASS= Direct job JCL statement to a specific input queue, installation specific

MSGCLASS= Direct job output to a specific output queue, installation specific

MSGLEVEL= Controls amount of system message to be received

EXEC statement The EXEC JCL statement //MYSTEP EXEC has a stepname of MYSTEP. Following the EXEC is either PGM=(executable program name) or a JCL PROC name. When a JCL PROC is present, then the operands will be the variable substitutions required by the JCL PROC. Common operands found on the EXEC PGM= statement are:

PARM= Parameters known by and passed to the program.

COND= Boolean logic for controlling execution of other EXEC steps in this job....IF, THEN, ELSE JCL statements exist that are superior to using COND, however, lots of old JCL may exist in production environments using this statement.

TIME= Imposes a time limit.

DD statement The DD JCL statement //MYDATA DD has a ddname of MYDATA.

DD, the Data Definition, has significantly more operands than the JOB or EXEC statements. The DD JCL statement can be involved with many aspects of defining or describing attributes of the program inputs or outputs. Some common DD statement operands are:

DSN= The name of the data set; this can include creation of temporary data sets or a reference back to the data set name.

DISP= Data set disposition at step start (new, shr, old, mod), at step end (catlg, keep, delete, pass) and if the step abnormally ends (catlg, keep, delete, pass).

SPACE= Amount of disk storage requested for a new data set. SYSOUT= Defines a print location (and the output queue or data set).

VOL=SER= Volume name, disk name or tape name

UNIT= System disk, tape, special device type, or esoteric (local name).

DEST= Routes output to a remote destination.

DCB= Data set control block, numerous sub operands.

Most common suboperands:

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LRECL= Logical record length. Number of bytes/characters in each record.

RECFM= Record format, fixed, blocked, variable, etc.

BLOCKSIZE= Store records in a block of this size, typically a multiple of LRECL. A value of 0 will let the system pick the best value.

DSORG= Data set organizationsequential, partitioned, etc.

LABEL= Tape label expected (No Label or Standard Label followed by data set location). A tape can store multiple data sets; each data set on the tape is in a file position. The first data set on tape is file 1.

SPOOLSPOOL

Initiator-Allocation

- Execution- Cleanup

Initiator-Allocation- Execution- Cleanup

submitJOBs

Printer

JES

Batch flow - JES

Notes:

What is JES?

In the z/OS operating system, JES manages the input and output job queues and data.

JES handles the following aspects of batch processing for z/OS:

Receives jobs into the operating system Schedules them for processing by z/OS Controls their output processing

JES is the component of the operating system that provides supplementary job management, data management, and task management functions such as scheduling, control of job flow, and spooling.

z/OS has two versions of job entry systems: JES2 and JES3. Of these, JES2 is most common by far and is used throughout this text.

Some important differences, but both JES2 and JES3:

Accept and queue jobs submitted for execution Queue jobs for an initiator -- a JES program that requests the next job in the queue Accept output from a job while it is running and queue the output Can print the output, or save it on spool for an output manager to retrieve.

The initiator is an integral part of z/OS that reads, interprets, and executes the JCL. It is normally running in several address spaces (as multiple initiators). An initiator manages the running of batch jobs, one at a time, in the same address space. If ten initiators are active (in ten address spaces), then ten batch jobs can run at the same time. JES does some JCL processing, but the initiator does the key JCL work.

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The jobs shown on the slide represent JCL and perhaps data intermixed with the JCL. Source code input for a compiler is an example of data (the source statements) that might be intermixed with JCL. Another example is an accounting job that prepares the weekly payroll for different divisions of a firm (presumably, the payroll application program is the same for all divisions, but the input and master summary files may differ).

The diagram represents the jobs as punched cards (using the conventional symbol for punched cards) although real punched card input is very rare now.

JES uses one or more disk data sets for spooling. JES combines multiple spool data sets (if present) into a single conceptual data set. The internal format is not in a standard access-method format and is not written or read directly by applications. Input jobs and printed output from many jobs are stored in the single (conceptual) spool data set. In a small z/OS system the spool data sets might be a few hundred cylinders of disk space; in a large installation they might be many complete volumes of disk space. Spool simply means to queue and hold data in card-image format (for input) or printed format (for output).

To run multiple jobs asynchronously, the system must perform a number of functions:

Select jobs from the input queues (JES does this). Ensure that multiple jobs (including TSO users and other interactive applications) do

not conflict in data set usage.

Ensure that single-user devices, such as tape drives, are allocated correctly. Find the executable programs requested for the job. Clean up after the job ends and then request the next job.

SDSF: Primary option menu

Notes: This is the SDSF primary options menu. Some of the options shown are:

DA The Display Active panel shows information about MVS address spaces (jobs, started tasks, and TSO users) that are running.

I The Input Queue panel displays information about jobs, started tasks, and TSO users on the JES2 input queue or executing.

O The Output Queue panel displays information about SYSOUT data sets for jobs, started tasks, and TSO users on any nonheld JES2 output queue. H The Held Output panel shows information about SYSOUT data sets for jobs, started tasks, and TSO users on any held JES2 output queue. ST The Status panel displays information about jobs, started tasks, and TSO users on the JES2 queues.

LOG The system Log panel displays the log and lets you search it. PS The Processes panel displays information about z/OS UNIX System Services processes. PR The Printers panel displays information about JES2 printers printing jobs, started task, and TSO user output.

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SDSF: Status panel

Notes:

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Unit 6

Transaction managers on z/OS

Example of online processing: a travel agencyC a r R e n ta l A g e n c y H o te l A i rl i n e

T ra ve l A g e n c y

W A P H T T P

Transaction managers on z/OS

Notes: Characteristics of a transactional systems:

Many users Repetitive Short interactions Shared data Data integrity Low cost / transaction

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z / O Sz / O S

T r a n s a c ti o n a ls y s te m

A p p l i c a t i o nA p p l i c a ti o nP r o g r a mP r o g r a mD A T AD A T A

U s e r

C Inf Cont Sustomer ormation rol ystem

CICS in a z/OS system

Notes: Transactional subsystem of z/OS which:

run online applications the same time, many users, same application(s) manages the sharing of resources integrity of data prioritization of execution, with fast response.

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Languages:- COBOL- OO COBOL- C- C++

- JAVA (JCICS)- PL/I- Assembler

Platforms:- zSeries (z/OS,

OS/390, VSE)

- Intel servers

- TXSeries (AIX, HP-UX, Solaris and Windows)

CICS - Languages & Platforms

Notes:

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BMS macros: a form of assembler language

ORCHM01 DFHMSD TYPE=MAP,MODE=INOUT,CNRL=FREEKB,LANG=COBOL,TIOAPFX=YESORCHM01 DFHMDI SIZE=(24,80)

DFHMDF POS=(01,01),LENGTH=01,ATTRB=(ASKIP,DRK,FSET), xINITIAL=1

DFHMDF POS=(01,25),LENGTH=3,ATTRB=(ASKIP,BRT), xINITIAL=PURCHASE ORDER - - - FILE INQUIRY

DFHMDF POS(03,30),LENGTH=13,ATTRB=ASKIP, xINITIAL=ORDER NUMBER

ORDER# DFHMDF POS=(03,44),LENGTH=10,ATTRB=(NUM,BRT,IC) DFHMDF POS=(04,32),LENGTH=11,ATTRB=ASKIP,INITIAL=DEPARTMENT

***

DFHMSD TYPE=FINAL

The MAPS are composed of three simple macros:DFHMSD name of mapsetDFHMDI name of map identificationDFHMDF field screen definitions and location

Example

BMS

Notes: You can have several maps within a mapset definition.

BMS macros: a form of assembler language Result of an assembles : Physical Map

Physical map contains info to :

build the screen merge variable data between program & screen send variables back to program

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A B CD A vera g e s ala ry b y d ep art m e nt

T yp e a d ep a rtm e nt n u m b er a nd p re ss en t er .

D ep a rtm e n t n u m b er: A0 2

A ver ag e s ala ry( $) : 58 211 .58

F 3 : E xit

Example of CICS application user screen

Notes:

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Unit 7

Database Manager on

z/OS

DB2 Concepts: Data Structures

What is a database?

A database provides for the storing and control of business information, independent from (but not separate from the processing requirements of) one or more applications.

Database Manager on z/OS

Notes: Why use a database?

Reduce programming effort Manage data more efficiently Easy to separate confidential/sensitive info Provide a greater level of security Access & update simultaneously Ensure consistency Provide backup and recovery Utilities to monitor and tune Structure change does not impact existing developments

Relational Structures include:

Database: A logical grouping of data for one or more applications Table: A logical structure composed of rows and columns Index(es): An ordered set of pointers to rows of a table (ensures uniqueness) Keys: One or more columns that are identified as such in the creation of a table or used

for referential integrity

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At the intersection of every column and row is aspecific data item called a value or more preciselyan atomic value

Example of a DB2 Department Table

Notes:

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Query Management Facility (QMF)

SQL Processor Using File Input (SPUFI)

Is a tightly integrated, powerful, and reliable tool that performs query and reporting for DB2. It offers an easy-to-learn, interactive interface. Users with little or no data processing experience can easily retrieve, create, update, insert, or delete data that is stored in DB2.

A SQL interface through TSO providing a means for a transactional facility used by DBAs. This requires knowledge of ISPF and basic PDS. Pronounced Spoo Fee

DB2 Administration (transactional interfaces)

Notes:

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The SPUFI edit panel: After entering an SQL statement

SPUFISPUFI Result Dataset from previous SQL

Notes:

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Unit 8

Security on z/OS

RACF and the other available packages are add-on products which provide the basic security framework on a z/OS mainframe

Identify and authenticate users Authorize users to access protected resources Log and report attempted unauthorized access Control means of access to resources

Security on z/OS - RACF

Notes: Why security?

Any system security must allow authorized users the access they need and prevent unauthorized access.

Many companies critical data is now on computer and is easily stolen if not protected z/OS Security Server provides a framework of services to protect data

Identification and verification of users RACF uses a userid and system encrypted password to perform its user identification and verification

The userid identified the person to the system

The password verifies the users identity

Passwords should not be trivial and exits can be used to enforce policies.

Protection Levels RACF works on a hierarchical structure

ALLOC allows data set creation and destruction

CONTROL allows VSAM repro

WRITE allows update of data

READ allows read of data

NONE no access

A higher permission implies all those below

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Protecting general resources Many system resources can be protected

DASD volumes

Tapes

CICS or IMS transactions

JES spool datasets

System commands

Application resources and many more

RACF is flexible and more can be added

RACF identifies you when you logon Userid and password are required Each RACF userid has a unique password Password is one way encrypted so no one else can get your password not

even the administrator

Userid is revoked after a preset number of invalid password attempts

RACF Structure Userid

Group Every userid belongs to at least one group Group structures are often used for access to resources

RACF - User Identification

Notes:

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