IBM Support

BUILDSSX(REBUILD) SSCMNAME(,TEMPORARY/PERMANENT) - CORRECT USAGE

Troubleshooting


Problem

The BUILDSSX() and SSCMNAME() parameters of the OPCOPTS initialization statement are often used incorrectly. Incorrect use of these parameters may cause loss of jobtracking information, and possibly may lead to ECSA fragmentation.

Resolving The Problem

The BUILDSSX() and SSCMNAME() parameters of the OPCOPTS initialization statement are intended to be used ONLY for two specific purposes.

1. To enable a user to implement maintenance updates to the TWSz subsystem code without requiring an IPL.

2. To enable TWSz users to migrate from one release of the product to another without an IPL.

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When a TWSz CONTROLLER or TRACKER started task is started with the BUILDSSX() option, the associated subsystem is completely rebuilt. If the REBUILD option is specified, the contents of the subsystem WTRQ are abandoned and a new WTRQ is created and initialized. Thus any events queued to the WTRQ before the TRACKER was started are lost. If BUILDSSX(MERGE) is specified, the subsystem is rebuilt with new code, but the contents of the existing WTRQ are copied to the one associated with the new subsystem. Thus, with MERGE, the events already on the WTRQ prior to starting the TRACKER are not lost.

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HOWEVER, because the structure of the WTRQ itself, and since the records queued are not guaranteed to be maintained from one release to the next, BUILDSSX(MERGE) should NEVER be used during a TWSz migration. When moving from one TWSZ release to another without an immediate IPL, the BUILDSSX(REBUILD) option must ALWAYS be used.

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When not changing TWSz RELEASES, but only applying maintenance that updates the EQQINITx lmod, but not the EQQSSCMx loadmod, it is permissible to use BUILDSSX(MERGE).

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When not changing TWSz Releases, but applying maintenance that updates the EQQSSCMx load module, it MAY be permissible to use BUILDSSX(MERGE). If you're in a high-volume production system, or make extensive use of Event Triggered Tracking, where it is not possible to quiesce the system so that the TRACKER can be restarted, you may wish to contact TWSz Software Support for guidance on using BUILDSSX(MERGE|REBUILD)

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If BUILDSSX is used in conjunction with the SSCMNAME() parameter, the processing is controlled by the SSCMNAME TEMPORARY/PERMANENT option.

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If SSCMNAME(xxxxxxxx,TEMPORARY) is used, the newly generated subsystem exists only until the TWSZ started task is stopped, then the previously existing subsystem is reinstated. If the PERMANENT option is used, the "old" subsystem is discarded and the dynamically created subsystem and associated WTRQ are used until the next IPL, when the subsystem is recreated from the values specified in the IEFSSNxx member of SYS1.PARMLIB.

NOTE: When SSCMNAME(xxxxxxxx,PERMANENT) is used, the load module specified must reside in an APF-authorized library defined in a STEPLIB DD in the started task JCL.

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Thus the BUILDSSX() and SSCMNAME() parameters should be inserted into the TWSz init member **ONLY** when a migration is actually being done, or maintenance is being applied, and should be removed as soon thereafter as possible.

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The best option is to start each task ONE TIME using the PERMANENT option, then immediately remove that option once the task is correctly initialized. The changes thus implemented will remain in effect until the next system IPL.

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If after a subsystem had been updated in this way, it becomes necessary to retreat to the prior level of code, the same parameters can be used to rebuild the subsystem again, this time using the "old" loadlib and the old EQQSSCMx module name.

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For detailed information on these parameters, see the TWSz CUSTOMIZATION AND TUNING manual for your current level of TWS-z/OS.

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Document Information

Modified date:
13 September 2019

UID

swg21265106