IV58073: WebSphere MQ channels cannot be configured to take the operatingsystem defaults for TCP/IP send and receive buffer sizes

APAR status

• Closed as program error.

Error description

• When working on high-latency networks WebSphere MQ's choice of
  32 KB TCP/IP buffer sizes can be non-optimal for use on that
  network.
  
  A user might analyse the network traffic at a low level and
  choose to override buffer sizes using qm.ini file settings like
  the ones listed below. But on some occasions a user might want
  WebSphere MQ to take no decision on TCP/IP buffer sizes, but
  allow the operating system to take its own decisions on these
  buffers.
  
  This APAR introduces a special value of zero for the qm.ini
  parameters listed below. The special value of zero means that
  WebSphere MQ channel programs (example: runmqchl, amqrmppa) will
  not ask the operating system to choose any particular values for
  the TCP/IP send and receive buffers. So the operating system
  TCP/IP stack will revert to its own default behaviour, which
  might be faster.
  
  List of the affected parameters in the TCP stanza : SndBuffSize,
  RcvBuffSize, RcvSndBuffSize, RcvRcvBuffSize, ClntSndBuffSize,
  ClntRcvBuffSize, SvrSndBuffSize, SvrRcvBuffSize
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users with high-latency networks in which WebSphere MQ's choice
  of 32 KB send and receive buffers might be non-optimal for that
  network.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM SUMMARY:
  WebSphere MQ always chose a value for TCP/IP send and receive
  buffers on the sockets it was using. Even if the user wanted to
  use operating system defaults for these buffers, a facility was
  not provided for the user to tell MQ to default.
  

Problem conclusion

• A zero value is now allowed for all of the parameters mentioned.
  For this APAR to have full effect, add the following in qm.ini.
  
  TCP:
     SndBuffSize=0
     RcvBuffSize=0
     RcvSndBuffSize=0
     RcvRcvBuffSize=0
     ClntSndBuffSize=0
     ClntRcvBuffSize=0
     SvrSndBuffSize=0
     SvrRcvBuffSize=0
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v7.0       7.0.1.13
  v7.1       7.1.0.6
  v7.5       7.5.0.2
  
  The latest available maintenance can be obtained from
  'WebSphere MQ Recommended Fixes'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
  
  If the maintenance level is not yet available information on
  its planned availability can be found in 'WebSphere MQ
  Planned Maintenance Release Dates'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
  ---------------------------------------------------------------
  

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:

Fix information

• Fixed component name

  WMQ LIN X86-64

• Fixed component ID

  5724H7230

Applicable component levels