PK37736: DOUBLE FREEMAIN OF FEPI CONTROL BLOCKS BY DFHSZRDC

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Message DFHRM0131 Resynchronization required with IRC resources
  followed by message
  DFHSM0002 A severe error (code X'0305') has occurred in DFHSMGF
  is issued at shutdown time due to double freemain issued by
  module DFHSZRDC to freemain FEPI control blocks.
    It is suspected FEPI received unsolicited BIND requests from
  the partner system at around the same time FEPI was shutting
  down. Possibly due to the partner system automatically
  re-connecting the sessions after FEPI terminated them once due
  FEPI shutdown.
  The terminate process sets the SZD_CD_DREASON shutdown bits on
  in the connections, so that when they were processed by DFHSZ2SC
  , DFHSZRDC is called to FREEMAIN them.
  However the connections were still waiting on the IRB queue
  and when this was processed DFHSZRDC was called again as
  SZD_CD_DREASON was still on resulting in the double FREEMAINs.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All CICS Users.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: Double FREEMAIN of FEPI control blocks  *
  *                      by DFHSZRDC.                            *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  During CICS termination FEPI connections are released before the
  DFHSZDCD connection block is freed by module DFHSZRDC. While
  DFHSZRDC is running an attempt is made to re-acquire the FEPI
  terminal causing an unsolicited BIND to drive the FEPI SCIP exit
  DFHSZYSC, which queues the connection on the FEPI IRB process
  queue. When the FEPI dispatcher subsequently removes the
  connection from the IRB queue the storage has already been
  freed, but as the delete flags are still set DFHSZRDC is called
  once again, leading to the reported double FREEMAIN failure.
  
  DFHSM0002 A severe error (code X'0305') has occurred in DFHSMGF.
  
  The failure occurred for a datastream connection. A similar
  problem could also occur for a formatted connection in which
  case different symptoms may result.
  
  Additional keywords: SZD_CD_DREASON SZD_DS_P1GPTR RDC:FPD
  SZD_CD_DSPTR RDC:DDS RDC:DCD MSGDFHSM0002 FPD DDS DCD ABEND0C4
  S0C4 0C4 DFHSZRDP
  

Problem conclusion

• CICS has been changed in the FEPI SCIP exit DFHSZYSC so that a
  connection which is in the process of being deleted will no
  longer be selected to satisfy an unsolicited BIND request.
  

Temporary fix

• FIX AVAILABLE BY PTF ONLY
  

Comments

APAR Information

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

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

  UK23238

Modules/Macros

•    DFHSZYSC
  

Fix information

• Fixed component name

  CICSTS 3.1 Z/OS

• Fixed component ID

  5655M1500

Applicable component levels

• R400 PSY UK23238

     UP07/03/23 P F703

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.