PI48766: MQ LISTENER STOPS WHEN LARGER TCP BUFFER SIZES REQUESTED WITHOUT THE PROPER TCPCONFIG SETTINGS TO ALLOW BUFFERS.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Chinit was set to use larger TCP/IP send or receive buffers.
  After the CHINs were restarted the LISTENER immediately stopped
  without any error messages explaining why:
  
  CSQX251I CSQXSTRL Listener started, TRPTYPE=TCP INDISP=QMGR
  CSQX023I CSQXLSTT Listener started,
   port <port> address *
   TRPTYPE=TCP INDISP=QMGR
  CSQX234I CSQXLSTT Listener stopped, TRPTYPE=TCP INDISP=QMGR
  
  
  The listener could not be dynamically started:
  CSQM134I CSQMSLIS START LISTENER TRPTYPE(TCP) COMMAND ACCEPTED
  CSQX017I CSQXSTRL Listener already started,
   port <port> address *,
   TRPTYPE=TCP INDISP=QMGR
  CSQ9023E CSQXCRPS ' START LISTENER' ABNORMAL COMPLETION
  
  STOPping and STARTing the LISTENER did not help. Recycling the
  CHIN did not help.
  
  When buffers were set to previous value, the listener stayed
  running.
  

Local fix

• PI10617 requires that TCP/IP maximum Send/Recv buffer sizes are
  configured so that the CHINIT will be able to set the requested
  2MB buffer. This needs to be done with the following settings
  in the TCPCONFIG:
  
  TCPMAXSNDBUFRSIZE 2048K
  TCPMAXRCVBUFRSUZE 2048K
  
  Note that these do not set the default buffer sizes for
  applications (e.g. MQ); they just allow applications to request
  buffers up to the specified size.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of WebSphere MQ for z/OS Version 8 *
  *                 Release 0 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: When using a mechanism to increase      *
  *                      channels' TCP/IP send or receive buffer *
  *                      sizes, customers may find that their    *
  *                      listeners terminate with message        *
  *                      CSQX234I and cannot be restarted        *
  *                      without recycling the channel initiator *
  *                      address space.                          *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  IBM MQ for z/OS provides mechanisms to increase the TCP/IP
  buffer sizes for channels. If a size is requested that exceeds
  the system-wide limit (as configured with TCPMAXSNDBUFRSIZE or
  TCPMAXRCVBUFRSIZE), then the listener will terminate immediately
  and cannot be restarted until the channel initiator address
  space is recycled.
  

Problem conclusion

• Processing has been amended to ensure that a failure to set a
  larger TCP/IP buffer size than permitted by the current system
  configuration does not result in the listener task terminating.
  000Y
  CSQXCLIT
  

Temporary fix

Comments

APAR Information

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

  PI48282

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

  UI32502

Modules/Macros

• CSQXCLIT
  

Fix information

• Fixed component name

  WMQ Z/OS 8

• Fixed component ID

  5655W9700

Applicable component levels

• R000 PSY UI32502

     UP15/12/15 P F512

Fix is available

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