CSM STORAGE DEBUG

By David Himmel IBM z/OS Comm Server Level 2

Purpose: Steps to approach a CSM storage problem.

l  This presentation is designed to provide diagnostic guidance for CSM storage usage issues.

Intro and Overview

l  Communication Storage Manager (CSM) allows VTAM and other applications to use the same buffer in order to reduce data movement in the system.

l  CSM interfaces with the host operating system (MVS/ESA) to provide the storage buffer.

l  CSM is used by various VTAM and TCP/IP

components.

External Symptoms

l  CSM storage problems are indicated mostly by IVT5506I IVTSMCEX STORAGE ALLOCATION FAILED messages.

l  Various CSM IVTxxxxI messages indicating a CSM ECSA or CSM FIXED shortage

CSM Messages continued

l  IVT5560I CSM ECSA STORAGE LIMIT EXCEEDED

l  IVT5561I CSM FIXED STORAGE LIMIT EXCEEDED

l  IVT5562I CSM ECSA STORAGE AT CRITICAL LEVEL

l  IVT5563I CSM FIXED STORAGE AT CRITICAL LEVEL

Other External Symptoms

l  CSM storage problems may also be accompanied by other symptoms such as:

l  IST564I STORAGE UNAVAILABLE: COMMON AREA

l  IST154I EXPANSION FAILED FOR IO BUFFER POOL

l  IST154I EXPANSION FAILED FOR TI BUFFER POOL

l  TCP ABEND4C5 l  ABEND878

Obtain a Dump for Debug

l  If a dump is not generated due to the nature of the error, please obtain a dump using the VTAM CSDUMP command for diagnosis.

l  Please refer to the following YouTube video for information on using the CSDUMP command:

l  http://www.youtube.com/watch?v=jrnho6aAl7U

Additional Documentation

l  Obtain a VTAM Display of CSM: l  D net,CSM,OWNERID=ALL to determine

how much storage is being used and by what job / ASID.

l  If the CSM display indicates the TCP/IP ASID owns the storage not being freed, then include the TCP/IP ASID in the CSDUMP command.

Additional CSM Displays

l  Please refer to the SNA Commserver Operations manual for detail on displays

l  D net,CSMUSE l  NOTE: Please add the OWNERID=ALL

parameter on the first issue to determine which ASID is the biggest user.

Dataspace Storage

l  If the CSM display output indicates the CSM storage growth is in one of the CSM dataspace pools, dump the dataspace named in the display output in addition to the dump of VTAM and TCP.

Dump the dataspace storage…

l  Command to dump CSM dataspace: DUMP COMM=(CSM dataspace dump) R xx,jobname=(net),DSPNAME=(1.dddddddd), STOR=(00000000,7FFFFFFF),sdata=(nuc,csa,rgn,lsqa,sqa,trt)

Dataspace dump continued

l  If the DISPLAY CSM output indicates TCP/IP owns the storage that is not getting freed, also dump the TCP/IP dataspace

l  r xx,sdata=(csa,sqa,rgn,trt,nuc),jobname=(tcpip),cont r yy,dspname=(1.*CSM,'tcpip'.*)

Dumps and Traces

l  For a full global list of documentation to gather for CSM storage problems, refer to IBM Tech note:

l  www-01.ibm.com/support/docview.wss?uid=swg21308302

Common causes

l  Fixing CSM storage shortages may be as easy as increasing the amount of CSM storage available

l  VTPRM00 sets parameters for the Communication Storage Manager (CSM). IVTPRM00 is read during CSM initialization.

IVTPRM00 Continued

l  The IVTPRM00 parameters can be changed without a re-IPL by issuing the VTAM MODIFY CSM command.

l  The default values for IVTPRM00 are 100 MEG for both FIXED and ECSA. We suggest that they be coded or defaulted to 100M MAX ECSA and 100M MAX FIXED.

IVTPRM00 Continued

l  Monitor the system for one week with DISPLAY CSM command to determine peak usage. Adjust IVTPRM00 MAX ECSA and MAX FIXED values to 1.5 times the highest value indicated in the DISPLAY CSM outputs.

l  ADDITIONAL NOTE: You must adjust your IEASYSxx CSA parm to include the additional amounts of ECSA that CSM will be using.

Recommended Fix List

l  Please refer to the IBM Technote mentioned previous for a list of recommended maintenance for known CSM issues.

Additional Reference Material

l  For additional information on CSM storage, please refer to the following:

l  Communications Server CSM Guide l  Communications Sever SNA Diagnosis

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