PH61931: IBM MQ Z/OS: CSQX053E CSQSNAP XFFSXCSFREEOWNEDBUFFERS OWNERS DIDN'T FREE THEIR BUFFERS

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• The CHIN job log has an error:
  CSQX053E CSQXFFST Error information recorded in
    CSQSNAP data set
  
  The CSQSNAP information has eyecatchers of xcsFreeOwnedBuffers
  and "Owner didn't free their buffers".
  
  The FFST is being issued to report the existence of an area of
  storage used by a channel that was not freed during the
  lifetime of the channel. The buffer contents represent a large
  number of message properties.
  
  There is a code path where a buffer like this can be allocated
  to contain message properties, but it will not be freed.
  

Local fix

• No workaround available.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
  *                 Release 3 Modification 0 and                 *
  *                 Release 4 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: Various symptoms can occur when client  *
  *                      applications MQPUT/MQGET messages using *
  *                      message handles containing many or      *
  *                      large message properties.               *
  *                      Possible symptoms can include:          *
  *                      - CSQX053E reporting an FFST in the     *
  *                      CSQSNAP DD. The FFST indicates an error *
  *                      in xcsFreeOwnedBuffers                  *
  *                      - Storage leak in the channel initiator *
  *                      address space, leading to eventual      *
  *                      storage exhaustion                      *
  *                      - Abend 0C4 in CSQXMPAP                 *
  *                      - Storage Overlay in the channel        *
  *                      initiator address space, leading to     *
  *                      unpredictable results                   *
  ****************************************************************
  A client application issued MQGET, requesting that any Message
  Properties associated with the returned message are returned in
  a Message Handle.
  After locating a suitable message, MQGET processing detected
  that the properties buffer provided with the Message Handle was
  too small for the amount of properties associated with the
  message, and allocated a new larger buffer for the properties,
  however the old buffer was not correctly freed, and the new
  buffer was allocated using a different storage tracking scheme
  than the original.
  The difference in storage tracking scheme resulted in
  subsequent operations to manage the buffer (for example,
  resizing or freeing the buffer) failing, leading to varying
  symptoms being seen.
  

Problem conclusion

• When the message properties buffer is resized, the new buffer
  will be allocated using the same storage tracking scheme as the
  original, and the original buffer will now be freed.
  

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:

  UO02601 UO02602

Modules/Macros

• CSQMALCH CSQMGET  CSQXMPAP
  

Fix information

• Fixed component name

  IBM MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels

• R300 PSY UO02602

     UP25/04/10 P F504 ¢

• R400 PSY UO02601

     UP25/04/10 P F504 ¢

Fix is available

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