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End Subsystem Options—Optimize Ending Your Subsystems

August 30, 2017

The End Subsystem (ENDSBS), End System (ENDSYS), and Power Down System (PWRDWNSYS) commands all have the End Subsystem Options (ENSSBSOPT) parameter. This is nothing new—it’s been there for a long time. In case you are now aware of this parameter, this blog is for you.

The End Subsystem Options (ENDSBSOPT) parameter allows you to specify options that can improve the performance for ending the subsystem. There are four options you can select with the ENDSBSOPT parameter; if you chose to not use the default, you can select any or all of the other three options.
  • *DFT – Default; no special ending options are used
  • *NOJOBLOG—No job log
    No job logs are produced for the jobs that are ended. Not writing job logs can significantly reduce the workload on the system when subsystems are ended or when you are going to restricted state. However, if a problem occurs, you will not have the job log for diagnostic purposes.
    If you want the performance boost of not writing the job logs, but want the job logs to exist, you should consider using pending job logs. See my previous blogs, Job Log Pending and Job Log Output for more information
    *CHGPTY—Change run priority
    The CPU priority of the ending jobs is made higher (worse priority) to reduce the impact on other running jobs. This option is ignored if the subsystem is ending controlled. But if the DELAY time limit expires, this option will take effect immediately.
  • *CHGTS – Change timeslice
    The timeslice of the ending jobs is changed to a lower value (smaller timeslice) to reduce the impact on other running jobs. Like the *CHGPTY parameter, this option is ignored if the subsystem is ending controlled. But if the DELAY time limit expires, this option will take effect immediately.
If you use *CHGPTY and *CHGTS, the ending jobs have less of an impact on other jobs in the system, but it may take longer for the jobs to end. This is a trade-off of ending time versus the impact on the system.

This support is also available with the Navigator GUI—when you chose to stop a subsystem, you can specify options to take when the jobs are ended.

Posted August 30, 2017 | Permalink

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