rexx.ppt

CTS-PAC Version 1.6 1

REXXREXXREXXREXX


ObjectivesObjectivesObjectivesObjectives

Introduction to REXX

Syntax and Functions

Advanced Concepts


IntroductionIntroductionIntroductionIntroduction

What is REXX ? Restructured EXtended eXecutor Interpreted command language Very useful for linking TSO, ISPF and other functions Useful for developing custom-made utilities


Features of REXXFeatures of REXXFeatures of REXXFeatures of REXX

Ease of use

Free format

Convenient built-in functions


Features of REXX Features of REXX (Cont...)(Cont...)Features of REXX Features of REXX (Cont...)(Cont...)

Debugging capabilities

Interpreted language

Extensive parsing capabilities


Components of REXXComponents of REXXComponents of REXXComponents of REXX

Instructions Built-in functions TSO/E external functions Data stack functions


InstructionInstructionInstructionInstruction

Keyword Tells the language processor to do something

Assignment Gives a value to a variable or changes the current value of a

variable

Label A symbolic name followed by a colon Identifies a portion of the exec Commonly used in subroutines and functions, and with the

SIGNAL instruction


Instruction Instruction (Cont...)(Cont...)Instruction Instruction (Cont...)(Cont...)

Null Comment or a blank line Ignored by the language processor Makes an exec easier to read

Command (both REXX commands and host commands)


Built-in functionsBuilt-in functionsBuilt-in functionsBuilt-in functions

These functions are built into the language processor Provide convenient processing options


TSO/E external functionsTSO/E external functionsTSO/E external functionsTSO/E external functions

Interact with the system Do specific tasks for REXX


Data stack functionsData stack functionsData stack functionsData stack functions

Store data for I/O Other types of processing


Syntax of REXXSyntax of REXXSyntax of REXXSyntax of REXX


Character Type of REXXCharacter Type of REXXCharacter Type of REXXCharacter Type of REXX

A REXX instruction can be in lower case, upper case, or mixed case

Alphabetic characters are changed to uppercase, unless enclosed in single or double quotation marks

The two types of quotation marks cannot be mixed If any word in the statement is a variable, REXX

substitutes the value


FormatFormatFormatFormat

REXX uses a free format A line usually contains one instruction except when it

ends with a comma (,) or contains a semi-colon (;). Comma is the continuation character Indicates that the instruction continues to the next line Semi-colon indicates the end of the instruction Used to separate multiple instructions on one line


Environment / AddressEnvironment / AddressEnvironment / AddressEnvironment / Address

ADDRESS TSO for native TSO commands ADDRESS ISPEXEC for ISPF services ADDRESS ISREDIT for ISPF edit macros These are required to invoke the environment for

function calls


Variables and expressionsVariables and expressionsVariables and expressionsVariables and expressions


VariablesVariablesVariablesVariables

Character or group of characters that represents a valuee.g. count = 1000

Variable names can consist of: A....Z / a - Z alphabetic 0....9 numbers @ # $ ¢ ? ! . _ special characters


Variables Variables (Cont...)(Cont...)Variables Variables (Cont...)(Cont...)

Restrictions on the variable name are: The first character cannot be 0 through 9 or a period (.) The variable name cannot exceed 250 bytes The variable name should not be RC, SIGL, or RESULT,

which are REXX special variables


ParsingParsingParsingParsing

Separates data by comparing the data to a template (or pattern of variable names)

Preserves the case of the input data PARSE UPPER converts data to uppercase Separators in a template can be

blank, string, variable, or number that represents column position



Blank - an example Each variable name gets one word of data in sequence

except for the last, which gets the remainder of the data PARSE VALUE ‘Value with Blanks.’ WITH pattern

type pattern contains ‘Value’ type contains ‘ with Blanks.’



Blank - another example PARSE VALUE ‘Value with Extra Variables.’ WITH

data1 data2 data3 data4 data5 data1 contains ‘Value’ data2 contains ‘with’ data3 contains ‘Extra’ data4 contains ‘Variables.’ data5 contains ‘’



Substitution - an example PARSE VALUE ‘Value with Periods in it.’ WITH pattern .

type . pattern contains ‘Value’ type contains ‘Periods’ the periods replace the words “with” and “in it.”



Separators - an example phrase = ‘Dun & Bradstreet’ PARSE VAR phrase part1 ‘&’ part2 part1 contains ‘Dun ’ part2 contains ‘ Bradstreet’



Number: Numbers in a template to indicate the column at which data must be separated Unsigned integer indicates an absolute column position and Signed integer indicates a relative column position



Absolute column position An unsigned integer or an integer prefixed with an equal

sign (=) in a template The first segment starts at column 1 and goes up to, but

does not include, the information in the column number specified

The subsequent segments start at the column numbers specified



Absolute column position - an example quote = ‘Dun & Bradstreet’ PARSE VAR quote part1 6 part2

part1 contains ‘Dun &’ part2 contains ‘Bradstreet’



Absolute column position - another example quote = ‘Dun & Bradstreet’ PARSE VAR quote part1 5 part2 7 part3 1 part4 part1 contains ‘Dun’ part2 contains ‘&’ part3 contains ‘Bradstreet’ part4 contains ‘Dun & Bradstreet’



Relative column position A signed integer in a template separates the data according

to relative column position The starting position is relative to the starting position of

the preceding part. Can be either positive (+) or negative (-)



Relative column position - an example quote = ‘Dun & Bradstreet’ PARSE VAR quote part1 +5 part2 +5 part3 part1 contains ‘Dun &’ part2 contains ‘ Brad’ part3 contains ‘street’



Variables Define and use variables to provide further flexibility of a

PARSE VAR instruction Define the variable prior to the parse instruction Enclose the variable in parenthesis - this variable must be

an unsigned integer Use a sign outside the parenthesis to indicate how REXX is

to interpret the unsigned integer REXX substitutes the numeric value for the variable



Variables - an example quote = ‘Dun & Bradstreet’ movex = 4 PARSE VAR quote part5 +6 part6 +4 part7

-(movex) part8 part5 contains ‘Dun &’ part6 contains ‘Brad’ part7 contains ‘street’ part8 contains ‘Bradstreet’


ExpressionsExpressionsExpressionsExpressions

Something that needs to be calculated/evaluated Consists of numbers, variables, or strings, and one or

more operators Four types of operators

Arithmetic Comparison Logical and Concatenation


Arithmetic OperatorsArithmetic OperatorsArithmetic OperatorsArithmetic Operators

Work on valid numeric constants or on variables that represent valid numeric constants + Add - Subtract -number Negate the number +number Add the number to 0


Arithmetic Operators Arithmetic Operators (Cont...)(Cont...)Arithmetic Operators Arithmetic Operators (Cont...)(Cont...)

* Multiply ** Raise a number to a whole number power / Divide % Divide and return a whole number without a

remainder (quotient only) // Divide and return the remainder only


Arithmetic Operators - Arithmetic Operators - PriorityPriority

Arithmetic Operators - Arithmetic Operators - PriorityPriority

Priority from maximum to minimum - + Prefix operators ** Power (exponential) * / % // Multiplication and division + - Addition and subtraction


Comparison operatorsComparison operatorsComparison operatorsComparison operators

Do not return a number value Return either a true or false response in terms of 1 or 0

respectively == Strictly Equal = Equal > Greater than < Less than >= Greater than or equal to <= Less than or equal to


Comparison operators Comparison operators (Cont...)(Cont...)Comparison operators Comparison operators (Cont...)(Cont...)

\== Not strictly equal \= Not equal >< Greater than or less than (same as not equal) \< Not less than \> Not greater than


Strictly Equal and Equal Strictly Equal and Equal OperatorsOperators

Strictly Equal and Equal Strictly Equal and Equal OperatorsOperators

When two expressions are strictly equal, everything including the blanks and case (when the expressions are characters) is exactly the same

When two expressions are equal, they are resolved to be the same


Logical OperatorsLogical OperatorsLogical OperatorsLogical Operators

Return a true (1) or false (0) value when processed Combine two comparisons and return the true (1) or

false (0) value depending on the results of the comparisons

Used in complex conditional instructions Can act as checkpoints to screen unwanted conditions


Logical Operators Logical Operators (Cont...)(Cont...)Logical Operators Logical Operators (Cont...)(Cont...)

The logical operators are & AND

Returns 1 if both comparisons are true | Inclusive OR

Returns 1 if at least one comparison is true && Exclusive OR

Returns 1 if only one comparison (but not both) is true Prefix \ Logical NOT

Returns the opposite response


Concatenation operatorsConcatenation operatorsConcatenation operatorsConcatenation operators

Combine two terms into one Terms can be strings, variables, expressions, or

constants Concatenation can be significant in formatting output


Concatenation operators Concatenation operators (Cont...)(Cont...)

Concatenation operators Concatenation operators (Cont...)(Cont...)

blank concatenate terms, one blank in betweene.g. TRUE BLUE result is TRUE BLUE

|| concatenate terms, no blanks in betweene.g. “a”||”.b” result is a.b

abuttal concatenate terms, no blanks in betweene.g. per_cent‘%’ if per_cent = 50, result is 50%


Overall Operator PriorityOverall Operator PriorityOverall Operator PriorityOverall Operator Priority

\ ¬ - + Prefix operators ** Power (exponential) * / % // Multiply and divide + - Add and subtract blank || abuttal Concatenation operators == = >< Comparison operators & Logical AND | && inclusive OR, exclusive OR


Control of Control of program flowprogram flow

Control of Control of program flowprogram flow


Conditional instructionsConditional instructionsConditional instructionsConditional instructions

Instructions which set up at least one condition in the form of an expression

IF/THEN/ELSE, and

SELECT/WHEN/OTHERWISE


IF constructIF constructIF constructIF construct

Can direct the execution of an exec to one of two choices

IF expression THEN instructionELSE instruction

for more than one instruction for a condition, begin the set of instructions with a DO and end them with an END


IF construct IF construct (Cont...)(Cont...)IF construct IF construct (Cont...)(Cont...)

IF expression THEN DO

instructioninstruction

ENDELSE

DOinstructioninstruction

END


SELECT constructSELECT constructSELECT constructSELECT construct

can direct the execution to one of many choices. SELECT

WHEN expression THEN instructionWHEN expression THEN instruction:OTHERWISEinstruction(s)

END


SELECT constructSELECT constructSELECT constructSELECT construct

for more than one instruction for a possible path, begin the set of instructions with a DO and end them with an END

However, if more than one instruction follows the OTHERWISE keyword, DO and END are not necessary


Looping instructionsLooping instructionsLooping instructionsLooping instructions

Tell the language processor to repeat a set of instructions

A loop can repeat a specified number of times or Can use a condition to control repeating Two types of loops

Repetitive repeat instructions a certain number of times Conditional use a condition to control repeating


Repetitive loopsRepetitive loopsRepetitive loopsRepetitive loops

Repeat a set of instructions a specified number of times e.g. DO i = 1 to 5

SAY “Hello !”END

The step can also be controlled e.g. DO i = 1 to 10 STEP 2

SAY “Hello !”END


Repetitive loopsRepetitive loopsRepetitive loopsRepetitive loops

DO FOREVER/END - infinite loopsEXIT when a condition is reached

LEAVE instruction - leaves the loope.g. DO FOREVER

IF X = 0 THEN LEAVE


Conditional loopsConditional loopsConditional loopsConditional loops

DO WHILE DO WHILE expression

instruction(s)END

Test the expression before the loop executes the first time and repeat only when the expression is true


Conditional loopsConditional loopsConditional loopsConditional loops

DO UNTIL DO UNTIL expression

instruction(s)END

Test the expression after the loop executes at least once and repeat only when the expression is false


Interrupt instructionsInterrupt instructionsInterrupt instructionsInterrupt instructions

Tell the language processor to leave the exec entirely or leave one part of the exec and go to another part either

permanently or temporarily These are

EXIT SIGNAL CALL/RETURN


EXITEXITEXITEXIT

Causes an exec to unconditionally end Return to where the exec was invoked Can also return a value to the caller of the exec


SIGNAL labelSIGNAL labelSIGNAL labelSIGNAL label

Interrupts the normal flow of an exec Causes control to pass to a specified label Unlike CALL, SIGNAL does not return to a specific

instruction to resume execution When SIGNAL is issued from within a loop, the loop

automatically ends


SIGNAL labelSIGNAL labelSIGNAL labelSIGNAL label

When SIGNAL is issued from an internal routine, the internal routine will NOT return to its caller

SIGNAL is useful for testing execs or to provide an emergency course of action

Should not be used as a convenient way to move (jump) from one place in an exec to another


CALL / RETURNCALL / RETURNCALL / RETURNCALL / RETURN

When calling an internal subroutine, CALL passes control to a label specified after the CALL keyword

When the subroutine ends with the RETURN instruction, the instructions following CALL are executed


CALL / RETURNCALL / RETURNCALL / RETURNCALL / RETURN

When calling an external subroutine, CALL passes control to the exec name that is specified after the CALL keyword

When the external subroutine completes, the RETURN instruction returns to where you left off in the calling exec


Functions and SubroutinesFunctions and SubroutinesFunctions and SubroutinesFunctions and Subroutines


FunctionsFunctionsFunctionsFunctions

Sequence of instructions that can Receive data Process that data, and Return a value

All functions return a value to the exec that issued the function call

Syntax is function(arguments) No space between the function name and the left

parenthesis


Functions - parametersFunctions - parametersFunctions - parametersFunctions - parameters

Up to 20 arguments separated by commas Blank function( ) Constant function(55) Symbol function(symbol_name) Literal function(‘With a literal string’) function(function(arguments))

Another function function(‘With a literal string’, 55, option)

Combination of argument types


Functions - TypesFunctions - TypesFunctions - TypesFunctions - Types

Built-in functions built into the language processor User-written functions --

Written by an individual user or supplied by an installation Internal function is part of the current exec that starts at a

label External function is a self-contained program or exec

outside of the calling exec


Built-in functionsBuilt-in functionsBuilt-in functionsBuilt-in functions


Arithmetic functionsArithmetic functionsArithmetic functionsArithmetic functions

ABS Returns the absolute value of the input number

DIGITS Returns the current setting of NUMERIC DIGITS

FORM Returns the current setting of NUMERIC FORM

FUZZ Returns the current setting of NUMERIC FUZZ

MAX Returns the largest number from the list


Arithmetic functionsArithmetic functionsArithmetic functionsArithmetic functions

MIN Returns the smallest number from the list specified

RANDOM Returns a quasi-random, non-negative whole number in the range specified

SIGN Returns a number that indicates the sign of the input number

TRUNC Returns the integer part of the input number, and optionally a specified number of decimal places


Comparison functionsComparison functionsComparison functionsComparison functions

COMPARE Returns 0 if the two input strings are identical Returns the position of the first character that does not

match

DATATYPE Returns a value indicating data type of the input string, such as a number or character

SYMBOL Returns this state of the symbol (variable, literal, or bad)


Conversion functionsConversion functionsConversion functionsConversion functions

Convert one type of data representation to another type of data representation

B2X Binary to hexadecimal C2D Character to Decimal C2X Character to Hexadecimal D2C Decimal to Character


Conversion functionsConversion functionsConversion functionsConversion functions

D2X Decimal to Hexadecimal X2B Hexadecimal to binary X2C Hexadecimal to Character X2D Hexadecimal to Decimal


Formatting functionsFormatting functionsFormatting functionsFormatting functions

CENTER/CENTRE Returns a string of a specified length with the input string centered in it, with pad characters added as necessary to make up the length

COPIES Returns the specified number of concatenated copies of the input string

FORMAT Returns the input number, rounded and formatted to the number of digits specified



JUSTIFY Returns a specified string formatted by adding pad characters between words to justify to both margins

LEFT Returns a string of the specified length, truncated or padded on the right as needed



RIGHT Returns a string of the specified length, truncated or padded on the left as needed

SPACE Returns the words in the input string with a specified number of pad characters between each word


String manipulating String manipulating functionsfunctions


ABBREV Returns a string indicating if one string is equal to the specified number of leading characters of another string

DELSTR Returns a string after deleting a specified number of characters, starting at a specified point in the input string

DELWORD Returns a string after deleting a specified number of words, starting at a specified word in the input string




FIND Returns the word number of the first word of a specified phrase found within the input string

INDEX Returns the character position of the first character of a specified string found in the input string

INSERT Returns a character string after inserting one input string into another string after a specified character position




LASTPOS Returns the starting character position of the last occurrence of one string in another

LENGTH Returns the length of the input string

OVERLAY Returns a string that is the target string overlaid by a second input string




POS Returns the character position of one string in another

REVERSE Returns a character string, the characters of which are in reverse order (swapped end for end)

STRIP Returns a character string after removing leading or trailing characters or both from the input string




SUBSTR Returns a portion of the input string beginning at a specified character position

SUBWORD Returns a portion of the input string starting at a specified word number

TRANSLATE Returns a character string with each character of the input string translated to another character or unchanged




VERIFY Returns a number indicating whether an input string is composed only of characters from another input string or returns the character position of the first unmatched character

WORD Returns a word from an input string as indicated by a specified number

WORDINDEX Returns the character position in an input string of the first character in the specified word




WORDLENGTH Returns the length of a specified word in the input string

WORDPOS Returns the word number of the first word of a specified phrase in the input string

WORDS Returns the number of words in the input string


Miscellaneous functionsMiscellaneous functionsMiscellaneous functionsMiscellaneous functions

ADDRES Returns the name of the environment to which commands are currently being sent

ARG Returns an argument string or information about the argument strings to a program or internal routine

BITAND Returns a string composed of the two input strings logically ANDed together, bit by bit



BITOR Returns a string composed of the two input strings logically ORed together, bit by bit

BITXOR Returns a string composed of the two input strings eXclusive ORed together, bit by bit

CONDITION Returns the condition information, such as name and status, associated with the current trapped condition



DATE Returns the date in one of various optional formats

ERRORTEXT Returns the error message associated with the specified error number

EXTERNALS Returns the number of elements in the terminal input buffer. In TSO/E, always a 0

LINESIZE Returns the current terminal line width minus 1



QUEUED Returns the number of lines remaining in the external data queue at the time when the function is invoked

SOURCELINE Returns either the line number of the last line in the source file or the source line specified by a number

TIME Returns the local time in the default 24-hour clock format (hh:mm:ss) or in one of various optional formats



TRACE Returns the trace actions currently in effect

USERID Returns the TSO/E user ID, if the REXX exec is running in the TSO/E address space

VALUE Returns the value of a specified symbol and optionally assigns it a new value

XRANGE Returns a string of all 1-byte codes (in ascending order) between and including specified starting and ending values


Date formatsDate formatsDate formatsDate formats

Syntax of the date function id DATE(option) A variety of options are available The full option, or it’s first alphabet, can be passed as

argument A list of options follows



Base(or Basedate) Returns the number of complete days (that is, not including the current day) since and including the date, January 1, 0001, in the format: dddddd (no leading zeros or blanks) The expression DATE(‘B’)//7 returns a number in the range

0-6, where 0 is Monday and 6 is Sunday Thus, this function can be used to determine the day of the

week independent of the language



Century Returns the number of days, including the current day, since and including January 1 of the last year that is a multiple of 100 in the format: ddddd (no leading zeros)Example: A call to DATE(C) is made on March 13, 1992, so the number of days from January 1, 1900, to March 13, 1992, (33675) is returned

Days Returns the number of days, including the current day, so far in this year in the format: ddd (no leading zeros or blanks)



European Returns date in dd/mm/yy format

Julian Returns date in yyddd format

Month Returns full English name of the current month, for example, August

Normal Returns date in the format: dd mon yyyy. This is the default



Ordered Returns date in the format: yy/mm/dd (suitable for sorting)

Standard / Sorted Returns date in the format: yyyymmdd (suitable for sorting)

USA Returns date in mm/dd/yy format

Weekday Returns the English name for the day of the week, in mixed case, for example, Tuesday


Time formatsTime formatsTime formatsTime formats

Syntax of the Time function is TIME(option) A variety of options are available The full option, or it’s first alphabet, can be passed as the

argument A list of options follows



Civil Returns the time in Civil format: hh:mmxx The hours take the values 1 through 12 The minutes take the values 00 through 59 The minutes are followed immediately by the letters am or

pm The hour has no leading zero The minute field shows the current minute (rather than the

nearest minute) for consistency with other TIME results



Elapsed Returns sssssssss.uuuuuu, the number of

seconds.microseconds since the elapsed-time clock was started or reset

No leading zeros or blanks Setting of NUMERIC DIGITS does not affect the number The fractional part always has six digits



Hours Returns up to two characters Gives the number of hours since midnight Format is hh No leading zeros or blanks, except for a result of 0



Long Returns time in the format: hh:mm:ss.uuuuuu (uuuuuu is in

microseconds) The first eight characters of the result follow the same rules

as for the Normal form The fractional part is always six digits



Minutes Returns up to four characters Gives the number of minutes since midnight Format is mmmm No leading zeros or blanks, except for a result of 0



Normal This is the default Returns the time in the format hh:mm:ss Hours take the values 00 through 23 Minutes and seconds take 00 through 59 All these are always two digits Any fractions of seconds are ignored (times are never

rounded up)



Reset Returns sssssssss.uuuuuu, the number of

seconds.microseconds since the elapsed-time clock was started or reset

Also resets the elapsed-time clock to zero The number has no leading zeros or blanks Setting of NUMERIC DIGITS does not affect the number The fractional part always has six digits



Seconds Returns up to five characters Gives the number of seconds since midnight Format is sssss No leading zeros or blanks, except for a result of 0


SubroutinesSubroutinesSubroutinesSubroutines



Series of instructions that an exec invokes Performs a specific task The subroutine is invoked by the CALL instruction When the subroutine ends, it returns control to the

instruction that directly follows the subroutine call The instruction that returns control is the RETURN

instruction



Subroutines may be Internal and designated by a label, or external and designated by the member name that contains

the subroutine

IMPORTANT NOTE Internal subroutines generally appear after the main part of

the exec. So, when there is an internal subroutine, it is important to end the main part of the exec with the EXIT instruction


Using subroutinesUsing subroutinesUsing subroutinesUsing subroutines

Sharing information can be done by

Passing variables

Passing arguments


Passing VariablesPassing VariablesPassing VariablesPassing Variables

Main exec and subroutine share the same variables by name

Value of the variable is the same irrespective of where it has been set


An exampleAn exampleAn exampleAn example number1 = 5 number2 = 10 CALL sub1 SAY answer

(Displays 15) EXIT

sub1: answer = number1 +

number2 RETURN


Shielding VariablesShielding VariablesShielding VariablesShielding Variables

Done by using PROCEDURE instruction immediately after the subroutine label

All variables used in the subroutine become local to the subroutine

Shielded from the main part of the exec


An exampleAn exampleAn exampleAn example number1 = 10

CALL sub2 SAY number1 number2

(displays 10 NUMBER2) EXIT

sub2: PROCEDURE number1 = 7 number2 = 5 RETURN


Exposing VariablesExposing VariablesExposing VariablesExposing Variables

To protect specific variables use the EXPOSE option with the PROCEDURE instruction

followed by the variables that are to remain exposed to the subroutine


An exampleAn exampleAn exampleAn example number1 = 10 CALL sub3 SAY number1 number2

(displays 7 NUMBER2) EXIT

sub3: PROCEDURE EXPOSE number1

number1 = 7 number2 = 5 RETURN


Passing ArgumentsPassing ArgumentsPassing ArgumentsPassing Arguments

Passed in main EXEC by CALL subroutine_name argument1, argument2,

argument3, etc. Up to 20 arguments can be passed

Received in subroutine by ARG arg1, arg2, arg3, etc. The names of the arguments on the CALL and the ARG

instructions need not be the same information is passed by position, and not by name


An exampleAn exampleAn exampleAn example length = 10 width = 7 CALL sub4 length, width SAY ‘The perimeter is ‘

RESULT ‘Meters’ EXIT

sub4: ARG len, wid perim = 2 * ( len + wid) RETURN perim


Compound variablesCompound variablesCompound variablesCompound variables

Compound variable is a single-dimensional array, denoted by <variable name>.

The variable name itself can be more than one level The rules that apply to a variable name also apply to a

compound variable Very useful in array manipulation, input/output etc.


Using REXXUsing REXXUsing REXXUsing REXX


ConventionsConventionsConventionsConventions

Datasets are named as<high level qualifier>.REXX.EXEC

The last level .EXEC is optional Each member must have the first line as /* REXX */ This makes the command processor (TSO) invoke the

REXX interpreter


ConcatenationsConcatenationsConcatenationsConcatenations

Datasets containing REXX EXECs must be concatenated to SYSEXEC or SYSPROC

Concatenation to SYSEXEC makes execution faster, as it is above SYSPROC in the search order


MODEL commandMODEL commandMODEL commandMODEL command

Useful for giving an on-line model for ISPF function calls Edit a member in a REXX dataset, and issue the MODEL

command A list of all ISPF services is displayed Choose the desired service A copy of the syntax is embedded Change it as required


ExecutionExecutionExecutionExecution

How and where can REXX execs be executed From TSO READY prompt (if no ISPF services are used) From inside ISPF From inside another exec


Debugging REXX ExecsDebugging REXX ExecsDebugging REXX ExecsDebugging REXX Execs

TRACE C any command that follows is traced before it is executed then it is executed, and the return code from the command

is displayed

TRACE E any host command that results in a non-zero return code is

traced after it executes the return code from the command is displayed



Trace ?I (Intermediates) Stops execution after each instruction

Trace ?R (Results) Displays the result of execution of each step, but runs

continuously

These help to trace the progress of the EXEC EXECUTIL TS (Trace start) and TE (trace end) can also

be used to start and end the tracing of a REXX



RC Return code of the last instruction executed SIGL Set to the line number from where the transfer

occurred These variables can also be used to trace the exec


TSO/E External functionsTSO/E External functionsTSO/E External functionsTSO/E External functions

All TSO commands can be issued Enclose them within quotation marks

e.g. "LISTDS ‘my.dataset’ STATUS"

Variables can also be passed e.g. "LISTDS" name "STATUS" here, name is a variable used in the REXX


ISPF functionsISPF functionsISPF functionsISPF functions


PanelsPanelsPanelsPanels

Display panels, accept data and pass on data for processing

Syntax is ADDRESS ISPEXEC “Display panel(XXXXXX)”


TablesTablesTablesTables

All table services like TBCREATE, TBADD, TBUPDATE, TBDELETE etc.

Syntax is ADDRESS ISPEXEC “TBADD tbl-name ....” “TBDELETE tbl-name...” etc.


SkeletonsSkeletonsSkeletonsSkeletons

ISPF Skeleton services like generating JCLs from skeletons

Syntax is ADDRESS ISPEXEC “ftopen” “ftincl skelname” “ftclose temp” ADDRESS TSO “submit ztempf”


LM FunctionsLM FunctionsLM FunctionsLM Functions

Dataset list Member list

Copy members Delete members manipulate statistics of members


Data stackData stackData stackData stack

Place for storing variables temporarily Manipulated using PUSH and QUEUE No limits on the length and format of the data items Theoretically no limit on the number of items to be

stacked - limited only by practical considerations


Data stackData stackData stackData stack

PUSH works LIFO (Last-In-First-Out) puts items to the top of the stack

QUEUE works FIFO (First-In-First-Out) puts items on the bottom of the stack

In both cases, elements are removed by PULL QUEUED() gives the number of items put on a stack in

a single EXEC


Input/Output processingInput/Output processingInput/Output processingInput/Output processing

Operations with datasets All datasets with a defined record format are allowed

(except RECFM=U)


DISKRDISKRDISKRDISKR

EXECIO DISKR for reading the dataset/member “EXECIO 0 DISKR mydd (OPEN” - just opens the dataset “EXECIO 25 ...”- reads 25 lines “EXECIO * ...” - reads all the lines “EXECIO * DISKR myindd 100 (FINIS” - reads all

lines from line 100 In all the above cases, the lines are read on to the STACK

“EXECIO * DISKR myindd (STEM newvar.” - reads into a stem of variables called newvar


DISKWDISKWDISKWDISKW

Options for DISKR also hold for DISKW Writes to dataset/member Can be written from stem/stack Numerous other options available for positioning,

skipping, LIFO/FIFO etc.


An exampleAn exampleAn exampleAn example

Use REXX to List all datasets following a particular pattern For each dataset, list all the members starting with a

particular pattern

This can be done by Using LMDLIST to get the dataset list Then using LMMLIST on each dataset to get the member

list Match patterns, and display appropriate members


ReferencesReferencesReferencesReferences

TSO/E Version 2 REXX/MVS User’s Guide TSO/E Version 2 REXX/MVS Reference Both these books are available on our file server

(IBM Book Manager for Windows) Programming in REXX by Charles Daney, J.Ranade

IBM series


Thank Thank You!You!

Thank Thank You!You!

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