PI53581: LOOP IN DFHZDSP BECAUSE THE RPL CHAIN ON THE HPO RPL COMPLETION QUEUE HAS BEEN CORRUPTED

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• CICS is looping in the TCP task in module DFHZDSP in the code
  at label TCZDSPH0. DFHZDSP is processing RPLs on the RPL
  completion queue (TCTVRPLQ) when HPO is active. The cause of
  the loop is either an Receive Any RPL is pointing to itself or
  two Receive Any RPLs are pointing to each other.
  In this case the customer has code that issues  CEMT SET VTAM
  CLOSED, then later issued CEMT SET VTAM OPEN, and there appears
  to be a timing issue where we are manipulating a receive any RPL
  causing it to be added to the  TCTVRPLQ  chain, when it was
  already on the chain.
  Additional Symptom(s) Search Keyword(s): KIXREVSCB loop looping
  DFHZDSP HPO TCZDSPH0 TCP HANG HUNG Not log on
  

Local fix

• Turn off HPO by changing the SIT parameter to HPO=NO.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All CICS users.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: The CICS TCP task loops in module       *
  *                      DFHZDSP at label TCZDSPH0 when VTAM HPO *
  *                      is active.                              *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  An EXEC CICS SET VTAM FORCECLOSE request was made to close the
  VTAM ACB. Then there was an EXEC CICS VTAM OPEN.
  CICS issued the request to VTAM to open the ACB and cleared
  the HPO completion queue (TCTVRPLQ). Following this a Receive
  Any (RA) RPL, relating to the time before the FORCECLOSE,
  was returned to CICS and added to the TCTVRPLQ queue.
  CICS processed this RPL and reissued it to VTAM before going on
  to reinitialize all the RA RPLs as part of the OPEN processing.
  As a result, the same RPL was issued to VTAM twice and, when
  both requests were returned and added to the TCTVRPLQ queue,
  this caused the loop.
  

Problem conclusion

• CICS has been changed so that the TCTVRPLQ is cleared at a later
  point in OPEN processing and any RPLs added before then are
  ignored.
  

Temporary fix

• FIX AVAILABLE BY PTF ONLY
  

Comments

APAR Information

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

  PI50344

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

  PI54209 UI34216 UI34217

Modules/Macros

• DFHZGRP  DFHZOPA
  

Fix information

• Fixed component name

  CICS TS Z/OS V5

• Fixed component ID

  5655Y0400

Applicable component levels

• R800 PSY UI34216

     UP16/01/15 P F601

• R900 PSY UI34217

     UP16/01/15 P F601

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.