PI52488: DLI EPRIVATE STORAGE GROWTH FROM LGWX BACKOUT CONTROL BLOCKS OCCASIONALLY NOT FREED.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• DLI Private eprivate storage growth due to LGWX backout
  control blocks occasionally not being freed.
  .
  LGWX pointers in PSTLOGBO or PSTLOGWX may not
  be freed by modules DFSRDBC0 and DFSRDBL0.
  .
  To ensure that LGWX blocks are not left in
  the DLI extended private storage, module
  DFSCWU00 will be used to unallocate the blocks
  prior to unallocating the DPST storage.
  

Local fix

• Set DFSPRP MINTHREAD/MAXTHREAD value equal to to each other
  to prevent deallocation of the DPST control block which causes
  the associated LGWX pointers in PSTLOGBO or PSTLOGWX to be
  cleared and the storage to be orphaned.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All IMS V14 users who have Full Function                     *
  * databases.                                                   *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * The user experienced a ABENDU0979 RC03                       *
  * in the DL/I SAS private region.                              *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * INSTALL CORRECTIVE SERVICE FOR APAR/PTF                      *
  ****************************************************************
  The user experienced a ABENDU0979 RC03 in the DL/I SAS
  private region.  After some diagnosis it was found that the
  DL/I SAS extended private storage was growing significantly.
  This storage growth was due to there being 38,000 LGWX blocks
  in the DL/I region.  The LGWX blocks were not being released.
  These LGWX blocks no longer pointed back to the PST which owned
  them at one time.
  
  The LGWX block is acquired at two different times.  The
  database back out module, DFSRDBC0, gets a LGWX work area to
  process the log records used by the module during backout.
  This LGWX block is pointed to in PSTLOGBO.  The second user of
  the LGWX block is the database change logger, DFSRDBL0.  This
  module will get the first LGWX block and place its address in
  PSTLOGWX.  Unlike the database backout module, the change
  logger may need to get more than one LGWX block.  The second
  through Nth LGWX block will each contain the next LGWX pointer
  starting at +X'00' of the current block.  The last LGWX will
  have a next LGWX pointer of zeros.  All of the LGWX blocks,
  except the first block acquired, used to log an update are
  released when the update is logged.  This is where a problem
  has been found.  The code which released the next LGWX block
  always used the current LGWX to begin its search of LGWX
  blocks to release.  The problem is that the current LGWX block
  may not contain a next pointer since it is the last block.
  This is a problem when the current block is the second through
  Nth LGWX blocks.  This means that these LGWX blocks will not
  be released.
  
  Additional Keywords: U0979 ABEND80A ABEND878
  

Problem conclusion

• Code has been added to the following modules to address the
  issue of the LGWX block not being released.
  
  ************
  * DFSRDBL0 *
  ************
  After label RDBLEXIT the code will try and release all of the
  LGWX work blocks except the first LGWX work block which is
  pointed to by the PST( PSTLOGWX ).  The code was changed to
  always pick up the next LGWX from the first LGWX pointed to
  in PSTLOGWX.
  
  The first LGWX work area will be freed later in DFSCWU00
  when a DPST or CPST is released.
  
  ************
  * DFSCWU00 *
  ************
  After label RELCB810 there is code to release the LGWX block
  pointed to by PSTLOGWX.  The code added by this APAR will
  now release the LGWX block pointed to by PSTLOGBO also.
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

APAR Information

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

  PI12028

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

  UI34123

Modules/Macros

• DFSCWU00 DFSRDBL0
  

Fix information

• Fixed component name

  IMS V14

• Fixed component ID

  5635A0500

Applicable component levels

• R400 PSY UI34123

     UP15/12/29 P F512

Fix is available

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