PI31467: WMQ CMQXRFPT ABEND0C4 PIC 11

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Change Team finds a client application is doing an MQGET with
  convert. Conversion of the message data fails. In this case a
  function is called to determine whether the conversion failure
  was the result of the data being larger than the available
  buffer. This function allocates a larger buffer and frees the
  original one. On return from the function, the calling code gets
  updated to refer to the new buffer, however there is a pointer
  into the buffer which does not get updated. This means it still
  points into the freed buffer leading to the ABEND0C4 when a
  field is accessed using that pointer.
  

Local fix

• NO LOCAL FIX
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of WebSphere MQ for z/OS Version 7 *
  *                 Release 1 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: Preforming MQGET calls with convert     *
  *                      through a channel can result in a large *
  *                      amount of storage use in the cases      *
  *                      where the message cannot be converted.  *
  *                      This results in MQGET calls returning   *
  *                      MQRC_BUFFER_LENGTH_ERROR (MQRC 2005)    *
  *                      after a large number of failed MQGETs   *
  *                      with MQRC_NOT_CONVERTED (MQRC 2119).    *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  During the message conversion for the MQGET with MQGMO_CONVERT,
  the conversion can fail due to the buffer being smaller than
  required to convert the message. This is expected and the
  staging buffer used is increased in size to handle this and the
  conversion is reattempted. However in the scenario where the
  conversion fails for another reason, the staging area is still
  increased and the conversion reattempted. This larger staging
  area is not decreased after this. This can result in a large
  amount of storage use when a channel performs many MQGET with
  conversion calls which fail.
  
  Additionally when large staging buffers are freed ,in some
  circumstance the freed staging buffer may still be referenced,
  resulting in a 0C4 abend.
  

Problem conclusion

• The processing around conversion has been updated to only
  increase the size of the staging buffer when the conversion
  failed as the staging buffer is not big enough to hold the
  converted message. This prevents the staging buffer being
  increased in size unnecessarily, stopping the storage shortage
  due to this issue. Additionally after expansion, it ensures
  that the new staging buffer is referenced.
  100Y
  CMQXRSTF
  

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:

  PI34149 UI25204

Modules/Macros

• CMQXRSTF
  

Fix information

• Fixed component name

  WMQ Z/OS V7

• Fixed component ID

  5655R3600

Applicable component levels

• R100 PSY UI25204

     UP15/04/17 P F504

Fix is available

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