PQ90467: ABEND4C5 RC=2500 ECSA SHORTAGE - LARGE CSM BUFFERS CONTAINING INBOUND PACKETS

Obtain the fix for this APAR.

APAR status

• Closed as unreproducible.

Error description

• Customer experienced high ECSA storage usage.  The storage was
  primarily CSM in subpool 231 key 6 with many allocations of
  size x'0001E000' which were CSM 60K buffers and size x'005A000'
  which were CSM 180K buffers.   The data in the buffers were
  inbound packets (starting with the media header and including
  IP and TCP headers and all the data).  The packets were 1500
  bytes.   This size of packets are normally processed with
  the headers in ECSA and the data in dataspace(complex unpacking)
  but the entire packet in ECSA indicates they were processed
  with simple unpacking.
  (Note: see the EZBIFOUT portion of MV26473)
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of the Communications Server for   *
  *                 z/OS Version 1 Release 4 IP                  *
  ****************************************************************
  * PROBLEM DESCRIPTION: High ECSA storage usage in              *
  *                      subpool 231 key 6                       *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  'Simple packing' puts the packets entirely in ECSA and
  'complex packing' puts the headers in ECSA and the data in
  dataspace.  'Complex packing' should be done when the majority
  of the packets are medium or large to use ECSA efficiently.
  Currently, if the majority was medium sized packets the packing
  would remain in the mode it was in last.
  +-------------------------------------------------------------+
  + Please check our Communications Server for OS/390 homepages +
  + for common networking tips and fixes.  The URL for these    +
  + homepages can be found in Informational APAR II11334.       +
  +-------------------------------------------------------------+
  

Problem conclusion

Temporary fix

Comments

• In EZBIFOUT, prior to this fix if the large packet percentage
  was less than 10% and the small packet percentage was less than
  60% the stack would remain in the last setting of our packing
  mode (usually simple)  Unpacking_Timer has been updated to set
  the interface to complex packing mode in this situation to
  improve ECSA storage utilization.
  

APAR Information

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

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

  UQ90582

Modules/Macros

• EZBIFOUT
  

Fix information

• Fixed component name

  TCP/IP V3 MVS

• Fixed component ID

  5655HAL00

Applicable component levels

• R140 PSY UQ90582

     UP04/08/19 P F408

Fix is available

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