PI90813: COULD SEE DELAYS WITH IPIC CONNECTIONS WITH TASKS SUSPENDED ON ENQUEUE ISSSENQP

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• You are running CICS TS and have IPIC connections to the
  CICS transaction gateway (CTG). There are delays with tasks
  in enqueue waits on ISSSENQP - ENQ on IP Sockets.  The owner
  of the ENQ is in a SOCKET SEND WAIT.  The ENQUEUE pool
  summary for  ISSSENQP, shows many tasks backed up on 2
  different Enqueue names.
  CICS uses the ISSSENQP ENQ to serialize access to the IPIC
  sockets when sending a response back to the CTG.  There is
  supposed to be 1 ENQ per socket, so with 15 IPCONNs installed
  there should be 30 ENQs. However, in the dump there are only
  the 2 different enqueue names being used. With only 2 ENQs,
  then any delay in sending a response back to an individual
  CTG will delay 50% of the mirror tasks running in CICS.
  The ENQ names CICS uses are based on the first 4 characters
  of the IPCONN name. In this case the 15 IPCONNs  to the CTG,
  all begin with the characters CICS, which is why there is
  only 2 enqueue names being used. This means we
  can only send 2 responses in parallel back to the CTG, which
  could cause delays.
  
  Additional Symptom(s) Search Keyword(s): KIXREVSLD
  

Local fix

• rename the IPCONNs so that the unique part of the name is in
  the first 4 characters.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All CICS users.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: Delay to IPIC connections with tasks    *
  *                      suspended on enqueue ISSSENQP.          *
  ****************************************************************
  * RECOMMENDATION: .                                            *
  ****************************************************************
  CICS is connected to CICS Transaction Gateway via IPIC, using
  IPCONN definitions with names greater than four characters in
  length.  CICS uses an ISSSENQP enqueue to serialise access to
  each IPIC socket when sending data.  However, these enqueue
  names are created using only the first four characters of each
  IPCONN name.  As a result, if two or more IPCONNs have the same
  four characters at the start of their name, they become
  serialised on the same enqueue which may reduce throughput.
  

Problem conclusion

• DFHISSR has been modified to use up to all eight characters of
  an IPCONN name in the enqueue name used to serialise the
  sending of data.
  

Temporary fix

Comments

APAR Information

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

  PI88732

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

  UI52528

Modules/Macros

• DFHISSR
  

Fix information

• Fixed component name

  CICS TS Z/OS V5

• Fixed component ID

  5655Y0400

Applicable component levels

• R800 PSY UI52528

     UP17/12/11 P F712

Fix is available

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