PH56905: CSQX513E CSQXPING CURRENT CHANNEL LIMIT EXCEEDED CAUSING AN OUTAGE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• There looks to be a timing window between a channel stopping
  and a REFRESH SECURITY TYPE(SSL) command being issued.
  When this happens, message: 'CSQX513E CSQ1 CSQXPING Current
  channel limit exceeded' shows in the CHINIT Joblog, causing an
  outage.
  
  It was determined, that rrxSecureRefreshEnv is called as part
  of REFRESH SECURITY TYPE(SSL) processing. It loops through all
  active channels in the status table and sets each channel's
  status to inactive, subsequently decrementing the NumInUse
  count. In an attempt to serialise with a running channel
  instance by locking the status table, it was determined that
  the serialisation is not airtight, leading to a timing window
  where both the Refresh SSL process and a stopping channel both
  decrement the NumInUse count, leading to the CSQX513E error.
  

Local fix

• Restart the CHINIT A/S
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
  *                 Release 3 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: After issuing an 'REFRESH SECURITY      *
  *                      TYPE(SSL)' command a channel with       *
  *                      SSL/TLS enabled fails to start and the  *
  *                      following messages are issued in the    *
  *                      Channel Initiator Address Space:        *
  *                                                              *
  *                      +CSQX513E +XXXX CSQXRESP Current        *
  *                      channel limit exceeded                  *
  *                      +CSQX599E +XXXX CSQXRESP Channel XXXXXX *
  *                      ended abnormally                        *
  ****************************************************************
  There is a timing window between SSL refresh processing and a
  channel instance ending.
  
  This timing window can allow multiple attempts to stop the same
  instance of the channel resulting in the usage count for the
  channel being decremented multiple times. This can result in
  subsequent attempts to start the channel failing with the
  reported symptoms.
  

Problem conclusion

• The timing window has been removed so multiple attempts to stop
  the same instance of a channel with SSL/TLS enabled will no
  longer be made.
  

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:

  UI95010

Modules/Macros

• CSQXRCML CSQXRCMS
  

Fix information

• Fixed component name

  IBM MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels

• R300 PSY UI95010

     UP24/01/18 P F401 ¢

Fix is available

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