OA70365: ABEND106 IN Z/OS DLA DUE TO PRIVATE STORAGE FRAGMENTATION AND MEMORY LEAK DURING DB2 DISCOVERY

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• During DB2 discovery, IZDDCMDI obtained 16,388 bytes for its
  IFI buffer but released only 16,384 bytes, leaking 4 bytes per
  execution. This left an orphaned X'0FF8' fragment in Subpool 0
  on each call. Over multiple DB2 commands, the private area
  became fragmented, causing subsequent LOAD requests
  to fail with ABEND 106.
  

Local fix

• IZDDCMDI now allocates and releases storage in matching,
  page-rounded lengths.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All z/OS DLA V320 users.                     *
  ****************************************************************
  * PROBLEM DESCRIPTION: During DB2 discovery, IZDDCMDI fails    *
  *                      with ABEND 106 when loading DB2 CAF     *
  *                      modules due to insufficient storage     *
  *                      available.                              *
  ****************************************************************
  When acquiring storage for the DB2 IFI command buffer, IZDDCMDI
  obtained 16,388 bytes ($16k + 4) but released only 16,384 bytes,
   leaking 4 bytes per invocation. This 4-byte discrepancy left
   an orphaned X'0FF8' (4,088-byte) fragment in Subpool 0 on
   every call. Over repeated discovery executions across DB2
   subsystems, the user private region became severely
   fragmented, preventing subsequent LOAD requests from
   finding sufficient contiguous storage and resulting in
   ABEND 106.
  

Problem conclusion

• Module IZDDCMDI has been updated to calculate dynamic buffer
  allocations on clean 4 KB page boundaries and ensure
  STORAGE RELEASE frees the exact page-rounded byte length
  obtained during both initial allocation and dynamic buffer
  extension.
  

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:

  UJ11031

Modules/Macros

• IZDDCMDI IZDRDLA
  

Fix information

• Fixed component name

  Z/OS DLA

• Fixed component ID

  5698A4700

Applicable component levels

• R320 PSY UJ11031

     UP26/10/23 P F610

Fix is available

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