PH24327: RECEIVE MANY SYSTEM DUMPS REQUESTED BY DFHIRP'S MESSAGE EXIT FRR FOLLOWED BY MANY OTHER 0C4 DUMPS WHICH ARE NOT EXPECTED

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• A CICS region starts receiving many, many system dumps with
  title:
  ' CICS SYSTEM DUMP REQUESTED BY DFHIRP'S MESSAGE EXIT FRR'
  
  DFHIRP will take this dump when it runs out of a fixed
  set of buffers to receive XCF messages. These buffers contain
  work arriving from other CICS regions. When looking at
  LOGDATA, we noticed 0C4's occurring after the 0C1, which is not
  expected.
  Following each 0C1 at offset x'3F78' into DFHIRP,
  was an 0C4, caused by a bad PSW address. This then percolated
  to another 0C4 in csect name: IXCS1STB.
  So there was a pattern of dumps- 0C1/0C4/0C4 -
  repeated over and over.
  
  Understanding why DFHIRP initiated the 0C1 dump,
  we found a task was in a loop on the QR TCB issuing
  EXEC CICS SYNCPOINT commands over and over.
  This prevented the CSNC task, who would process these XCF
  messages, from running. Since CSNC was not able to process
  these messages, the buffers filled up, ran out.
  In this situation, CICS forces an 0C1 branching to label
  IRSWMCEH.
  Control goes to routine
  IRMXFRR- the XCF Message Exit FRR, which
  issues an SDUMPX macro to take a dump titled:
  
  "CICS SYSTEM DUMP REQUESTED BY DFHIRP'S MESSAGE EXIT FRR'
  This is the 0C1 dump, which is the only one we expect.
  
  The code then issues the SETRP macro to set a return address and
  indicate 'retry'.  Here is where the problem is.
  CICS is passing R15 for this return address, which is incorrect-
  R15 cannot be used, only R2-R12 can be specified.
  This causes a wild branch when the retry is attempted, and the
  0C4.
  This APAR is being taken to address these subsequent 0C4s due
  to passing a bad return address on the SETRP macro.
  
  Additional Symptom(s) Search Keyword(s): KIXREVxxx
  ABEND0C1 ABEND0C4 Cross-System Coupling Facility XCF
  Functional Recovery Routine FRR ladder MRO session
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All CICS users                               *
  ****************************************************************
  * PROBLEM DESCRIPTION: DFHIRP can cause 2 unexpected 0C4       *
  *                      abends after running out of XCF buffer  *
  *                      space.                                  *
  ****************************************************************
  A looping task in a CICS region can prevent CICS transaction
  CSNC from removing messages from DFHIRPs buffers to CICS
  storage.
  
  If DFHIRP runs out of XCF buffer space it reports this by using
  an architected 0C1 abend.  A system dump is taken for this abend
  by DFHIRP's FRR routine.  After this, R15 is invalidly used as
  the RETADDR on a SETRP macro.  The use of R15 can cause 2
  additional and unexpected 0C4 abends, each of which cause their
  own system dump to be taken.
  
  It is possible for DFHIRP to report the XCF buffer space error
  condition multiple times in quick succession.  This results in
  a large number of SDUMP requests in a very short space of time,
  which may adversely affect other subsystems on the LPAR.
  

Problem conclusion

• DFHIRP has been changed to correct the register usage on the
  SETRP macro.  This prevents the unwanted 0C4 abends.
  
  DFHIRP has also been changed to add additional symptom
  information to the SDUMP that is taken.  This allows DAE to
  suppress any duplicate dumps.
  

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:

  UI69195 010PC2Ÿ 010PC2Ÿ UI69196 010PC2Ÿ 010PC2Ÿ 010PC2Ÿ

Modules/Macros

• DFHIRP
  

Fix information

• Fixed component name

  CICS TS Z/OS V5

• Fixed component ID

  5655Y0400

Applicable component levels

• R100 PSY UI69196

     UP20/04/28 P F004

• R200 PSY UI69195

     UP20/04/28 P F004

Fix is available

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