PH56171: DFHXFPC-COMM STORAGE VIOLATION CAUSED BY DFHXFP DETECTING CONTAINER "DFHCOMMAREA" WHEN THE COMMAREA IS PASSED IN SESSION TIOA

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Storage violation caused by DFHXFP (transformer_2) overlaying
  storage that was getmained to hold the commarea passed on a DPL
  LINK request.
  The length of the getmain for the commarea storage, prefixed
  "DFHXFPC-COMM", is based on the LENGTH option of the LINK
  command issued by the calling program.
  .
  In this instance, the calling region is a pre-5.6 release so is
  not capable of 32K support. CTS 5.6 introduced support for
  COMMAREAs greater than 24 KB using Channel DFHTRANSACTION and
  Container DFHCOMMAREA to pass the commarea data.
  The session TCTTE of the called program does not have the flag
  bit TCTEX32KC set, indicating 32K commareas not supported.
  
  Therefore, the commarea is passed using the traditional
  mechanism in the TIOA.
  .
  However, the TIOA also contains a header for container
  "DFHCOMMAREA", namely >DFHCHANDFHTRANSACTION &
  >DFHCHDRDFHCOMMAREA. The container data length is over 30K.
  
  This container data gets moved to the commarea storage
  "DFHXFPC-COMM", which is not large enough to accommodate this
  amount of data resulting in the trailing storage zone and
  several CICS control blocks being overlayed.
  .
  The application program linkage involves DPL requests between
  6.1 to 6.1 using "DFHCOMMAREA" container to pass the commarea
  and 5.4 to 6.1 using traditional commareas in the TIOA.
  It would appear the surprise  "DFHCOMMAREA" container is one
  used earlier for a DPL across a 6.1 to 6.1 connection.
  

Local fix

• Apply the 32K Feature-Toggle com.ibm.cics.dpl.32kcommarea=false
  will disable the capability to use the new DFHCOMMAREA mechanism
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All CICS users.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: Storage violation resulting in overlays *
  *                      of memory when COMMAREA over 24K are    *
  *                      used on DPL requests over an MRO        *
  *                      connection.                             *
  ****************************************************************
  When a COMMAREA over 24K is sent on a DPL request over an MRO
  connection, it is possible for transformer_2 logic to overlay
  the storage following the DFHXFPC-COMM area allocated to hold
  the COMMAREA.
  

Problem conclusion

• DFHXFP has been changed so that the storage violation will no
  longer occur.
  

Temporary fix

Comments

APAR Information

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

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

  PH56194 UI93364

Modules/Macros

• DFHXFP   DFHXFQ
  

Fix information

• Fixed component name

  CICS TS Z/OS V6

• Fixed component ID

  5655YA100

Applicable component levels

• R400 PSY UI93364

     UP23/08/31 P F308 ¢

Fix is available

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