PM66474: ABENDS S0C1 WILD BRANCH FROM DBFDCAP1 USING CHANGE DATA CAPTURE WITH DEDB. AR8 CONTAINS UNEXPECTED INVALID ALET

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Abend S0C1 wild branch to low core out of DBFDCAP1, Change
  Data Capture for DEDB.  Problem appears to be we are in AR
  mode and save our registers in subroutine call in work area
  pointed to by R8, which is PSTLOGWA and *not* in CDC dataspace.
  A call is made to DBFMBED0 including XM ISWITCH. Somewhere in
  this processing AR8 gets loaded with an ALET. Upon return,
  the reload of registers is from dataspace and not intended work
  area, and the BR R14 is a wild branch to low core.
  Normal IMS linkage does not support AR mode and doesn't save
  and restore the ARs. DBFDCAP1 should save and restore across
  external calls since it depends on AR contents.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: ALL IMSFP V11 DEDB FPBP64=Y DCAP and Local   *
  *                 VSO users.                                   *
  ****************************************************************
  * PROBLEM DESCRIPTION: ABENDS0C4 in DBFDCAP1 due to a polluted *
  *                      Access Register 8.                      *
  ****************************************************************
  * RECOMMENDATION: INSTALL CORRECTIVE SERVICE FOR APAR/PTF      *
  ****************************************************************
  While building the DCAP data, an external call (external to
  DBFDCAP1) returned with garbage in Access Register 8 ( AR8 )
  triggering an ABENDS0C4.
  
  DBFDCAP1 clears all access registers on entry, and remains in AR
  (access register) mode for most of the module.  During return
  from an internal subroutine while in AR mode, we loaded return
  information based on where GR8 ( general register 8 ) was
  pointing.  Since AR8 was polluted and we were in AR mode, we
  picked up garbage and took a bad branch.  This bad branch caused
  the ABENDS0C4.
  
  AR8 was most likely polluted by the call to DBFMBED0, which will
  reread data into a buffer.  During the I/O process, IMS calls
  external process, which is where AR8 seems to have been
  polluted.
  

Problem conclusion

• GEN:
  KEYWORDS:
  
  *** END IMS KEYWORDS ***
  DBFDCAP1:
    Cleared out AR8 at point of failure and prior return from
    module's subroutines.
  
  DBFMGNX1:
    Cleared out AR8 after use.  This did not cause the abend, but
    was found during PDI/PSI of the abend.
  
  DBFMGUX1:
    Cleared out AR5 after use.  This did not cause the abend, but
    was found during PDI/PSI of the abend.
  

Temporary fix

• *********
  * HIPER *
  *********
  The fix for this APAR is BAD.  If you need to apply
  the fix for this APAR to resolve a problem, you must
  also apply the fix for APAR PM71187.
  AE12/08/20
  

Comments

APAR Information

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

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

  PM66943 UK81172

Modules/Macros

•    DBFDCAP1 DBFMGNX1 DBFMGUX1
  

Fix information

• Fixed component name

  IMS V11

• Fixed component ID

  5635A0200

Applicable component levels

• R100 PSY UK81172

     UP12/11/21 P F211

Fix is available

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