PH52347: LOOP WHEN USING IGZXAPI TO OBTAIN WSA

APAR status

• Closed as program error.

Error description

• When a COBOL CLLE control block is overlaid, a looping condition
  may occur in IGZXAPI when attempting to obtain WSA.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of Enterprise COBOL 5 and later        *
  *                 releases running programs which call         *
  *                 the IGZXAPI API with function                *
  *                 code 7 or 8.                                 *
  ****************************************************************
  * PROBLEM DESCRIPTION: A call to IGZXAPI with function code 7  *
  *                      or 8 may never return, leading to       *
  *                      appear as if it's a program hang.       *
  *                                                              *
  *                      When a system dump is taken for the     *
  *                      hang and IPCS is used to read the dump  *
  *                      via VERBEXIT LEDATA 'ALL', the          *
  *                      following message may appear:           *
  *                      * WARNING  Formatting of control block  *
  *                      chain stopped. Possible loop in chain.  *
  ****************************************************************
  * RECOMMENDATION: Install the provided PTF.                    *
  ****************************************************************
  If a user application corrupts memory out of the application's
  scope and abends, any usage of system control blocks after
  that point may produce random results.  In this case, an abend
  handler that got control during an abend tried to call the
  IGZXAPI to retrieve some specific program information.
  The corruption of system control blocks lead to a recursive
  loop in the control blocks.
  
  IGZXAPI retrieves information from the COBOL internal control
  block called CLLE.  When these control blocks are
  accidentally corrupted prior to the call to IGZXAPI, a
  recursive loop may occur within the IGZXAPI routine.  In
  particular a sequence of x'40' (blank characters) written over
  these control blocks will cause the loop.
  
  COB0501T/K COB0502T/K COB0601T/K COB0602T/K COB0603T/K
  COB0604/K
  

Problem conclusion

• Due to the corruption of control blocks a recursive chain was
  created.   A fix to try to determine this condition has been
  developed and should catch the looping condition.
  
  For details on IGZXAPI function code 7 and 8 see the URL at:
  https://www.ibm.com/support/pages/node/242521
  https://www.ibm.com/support/pages/node/6243414
  

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:

Modules/Macros

• IGZCEV4  IGZCJNI2 IGZLLIBV IGZXAPI  IGZXCA31 IGZXCDA  IGZXD24
  IGZXDMR  IGZXJNI2 IGZXLPIO IGZXLPKA IGZXLPKB IGZXLPKC IGZXLPKD
  IGZXLPKE IGZXLPKF IGZXLPKG IGZXPK2
  

Fix information

• Fixed component name

  LE ENT COBOL LI

• Fixed component ID

  568819812

Applicable component levels

• R7C0 PSY UP

     C

• R7D0 PSY UP

     C