PI99642: SKA PROTOCOL CHANGES TO GET STACK DEFAULT BUFFER SIZES SKA MINIMUM BUFFER SIZES SET TO 1M

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• In a multiple TCP/IP stack environment the getsockopt for
  send/receive buffer sizes was done before a bind, taking the
  values from the default stack, which may be incorrect.
  
  The minimum buffer sizes are now set to 1M (from 256K) if
  allowed by site maximums.
  

Local fix

• Set all stack defaults to the value desired.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: Classic Federation, Version 11.3             *
  *                 Classic CDC for IMS, Version 11.3            *
  *                 Classic CDC for VSAM, Version 11.3           *
  *                 Data Replication for IMS, Version 11.3       *
  *                 Data Replication for VSAM, Version 11.3      *
  ****************************************************************
  * PROBLEM DESCRIPTION: SKT protocol does not acquire default   *
  *                      send/receive buffer sizes from the      *
  *                      correct TCP/IP stack when multiple      *
  *                      stacks are active on the LPAR.          *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The SKT protocol uses getsockopt to obtain the default send/recv
  buffer sizes for the TCP/IP stack.  If the size was less than
  262144 the SKT protocol would setsockopt to 262144, subject to
  the stack maximum values.  If the default was configured to be
  greater than 262144 then the SKT protocl was supposed to use
  that value.  In a common INET configuration (i.e. multiple
  TCP/IP stacks running on the LPAR) that was not always the
  case.
  

Problem conclusion

• The SKT protocol was found to be doing the getsockopt/setsockopt
  calls prior to binding the port, which meant there was no
  affinity to any specific TCP/IP stack in an environment where
  multiple exist.  The value returned was based on the default
  TCP/IP stack and that might be different from the stack the port
  is eventually bound to.
  
  The SKT protocol was modified to do the getsockopt/setsockopt
  calls after binding the port, but before calling the listen or
  accept APIs.
  
  The code was also modified to set a minimum of 1M for these
  buffers instead of 262144; subject to stack maximums configured
  through TCPMAXSENDBUFRSIZE and TCPMAXRCVBUFRSIZE.
  

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:

  UI57168

Modules/Macros

•    CECCSKA
  

Fix information

• Fixed component name

  CLASSIC FED & E

• Fixed component ID

  5697I8200

Applicable component levels

• RB30 PSY UI57168

     UP18/07/11 P F807

Fix is available

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