PK52909: ABEND0C4 OCCURS USING FCPH CHAIN IN THREADSAFE ENVIRONMENT

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• An 0C4 occurs when both the transformers running on QR and
  threadsafe file control tasks are using the FCPH chain. The 0C4
  can appear in DFHXFP and file control modules depending on which
  task attempts to use the corrupted storage first.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All.                                         *
  ****************************************************************
  * PROBLEM DESCRIPTION: 0C4 occurs in DFHXFP when shipped and   *
  *                      threadsafe local file control requests  *
  *                      are run in the same region.             *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  0C4 occurs in DFHXFP when threadsafe file control work is also
  running. The FCPH buffer chain is being corrupted such that the
  forward chain pointer is being corrupted with data. There
  exists a timing window such that a task running threadsafe
  issues a file control requests against a local VSAM file and
  requires a buffer area, attempts to pull off a buffer area at
  the head of the chain just as a task is function shipped on QR
  and DFHXFP also needs a buffer area. Both tasks can use tha
  same buffer area which can lead to corruption on the FCPH
  chain when one of the tasks puts the buffer back onto the
  free chain.
  A similar abend0c4 can occur in DFHFCVS.
  Additional keywords
  XFX DFHXFX FCVS XFP S0c4 abendS0c4
  

Problem conclusion

• The FCPH chain was corrupted due to the use of an OC instruction
  to test the head of the chain in DFHXFP. This caused a change
  made by a CDS instruction to be overwritten and storage to be
  used by 2 tasks at the same time.
  The OC instruction is redundant and has been removed.
  

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:

  UK30268

Modules/Macros

•    DFHMBMBI DFHXFP   DFHXFX
  

Fix information

• Fixed component name

  CICSTS V3 Z/OS

• Fixed component ID

  5655M1500

Applicable component levels

• R500 PSY UK30268

     UP07/10/19 P F710

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.