PI70439: ASSIGNED BUT UNUSED PAGE FRAMES FOR ABOVE THE BAR STORAGE IS NOT A NECESSITY FOR THE PROFILE OF STORAGE USE BEING SEEN

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• IIDR CDC for z/OS uses above the bar (64 bit addressable)
  virtual storage for various purposes.  This virtual storage can
  be obtained in large amounts and used for a relatively short
  period of time, after which it is released.  The IARV64
  DISCARDDATA z/OS service is used to set the virtual storage's
  associated page frames as no longer in use by the address
  space.  KEEPREAL=YES is specified on the macro to retain the
  page frames, should the virtual storage be needed again soon.
  The profile of this storage use is such that it is unlikely
  that the storage will be used again relatively soon.
  KEEPREAL=NO should be specified, so that the page frames are
  immediately available for use by other address spaces without
  having to be stolen first.  This will also save processing
  costs for the IARV64 DISCARDDATA request
  

Local fix

• No local fix is available
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of IIDR CDC for z/OS who process very  *
  *                 large URs for replication.                   *
  ****************************************************************
  * PROBLEM DESCRIPTION: When large URs are held in a Staging    *
  *                      Space, a large amount of above-the-bar  *
  *                      storage will be allocated.  After the   *
  *                      UR has been transmitted, the storage    *
  *                      is no longer needed.  To prevent paging *
  *                      or swapping the storage, the IARV64     *
  *                      DISCARDDATA service is used to mark the *
  *                      page frames as unused.  KEEPREAL=YES is *
  *                      defaulted.  This will keep the page     *
  *                      frames allocated to the address space   *
  *                      unless they are stolen.  CLEAR=YES is   *
  *                      also specified, so that the data is     *
  *                      removed from the frames.  KEEPREAL=NO   *
  *                      should be used to make the frames more  *
  *                      immediately available for reuse by      *
  *                      other address spaces.  This will also   *
  *                      force CLEAR=NO, saving the CPU cost of  *
  *                      clearing the page frames.               *
  ****************************************************************
  * RECOMMENDATION: APPLY CORRECTIVE SERVICE                     *
  ****************************************************************
  
  KEEPREAL=YES on the IARV64 DISCARDDATA macro instruction causes
  page frames to remain allocated until they are stolen.
  

Problem conclusion

• The IARV64 DISCARDDATA will be coded with KEEPREAL=NO.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UI42150

Modules/Macros

• CHCGSSSW CHCSMGSW
  

Fix information

• Fixed component name

  INFO SRVR CDC Z

• Fixed component ID

  5655U7600

Applicable component levels

• RA21 PSY UI42150

     UP16/11/08 P F611

Fix is available

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