PK25872: MSGFPX0061E OCCURS RUNNING FPO POINTER CHECKER WHEN SEGMENT TWIN CHAIN IS GREATER THEN 1000K

APAR status

• Closed as program error.

Error description

• Pointer Checker receives:
  FPX0061E  -> Severe Error:
  FPX0061E Possible loop in segment twin chain.
  The error occurs when FPO checks the twin chain loop and
  encounters greater then 1 million twin segments in the chain.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All Online Pointer Checker users of High     *
  *                 Performance Fast Path Utilities FP Online    *
  *                 Tools Version 2 Release 1 (FMID: H31A210).   *
  ****************************************************************
  * PROBLEM DESCRIPTION: Forward Fit of FPO V2R1 APAR PK25746.   *
  *                      FP Online Pointer Checker (OPC) gets    *
  *                      FPX0061E message when encounters        *
  *                      greater than one million twin segments  *
  *                      in the chain.                           *
  ****************************************************************
  * RECOMMENDATION: Apply the maintenance for this APAR.         *
  ****************************************************************
  Forward Fit of FPO V2R1 APAR PK25746.
  OPC follows a twin chain during pointer checking.
  When the twin segment count exceeded the threshold value of
  OPC that was defined one million, OPC regarded the threshold
  value of the twin segment as a loop and issued the following
  messages:
  
    FPX0061E  -> Severe Error:
    FPX0061E Possible loop in segment twin chain.
  
  After issuing above messages, OPC continued processing and ended
  with RC=04.
  

Problem conclusion

• The area has actually more than one million twin segments so
  that it is not a twin chain loop.
  The threshold value of the twin segment count to be assumed
  as loop has been changed into two million from one million.
  Furthermore, the message-ID issued has been also changed into
  FPX0171W from FPX0061E because the program can not determine
  it is actually loop situation.
  
    FPX0171W  -> Warning:
    FPX0171W Possible loop in segment twin chain.
  
  The macro FPXMBLK has been modify to change the threshold value
  of the twin segments to be assumed as loop.
  The module FPXAERR0 has been modified to issue the new message
  FPX0171W at exceeding the twin segments threshold value.
  The module FPXMSG00 has been modify to introduce the new
  message FPX0171W.
  
  ---------------------------------------------------------------
  Documentation Changes:
  The IMS High Performance Fast Path Utilities for z/OS
  User's Guide Volume 3: Fast Path Online Tools (SC18-9239-00)
  should be changed as follows:
  
  Part 1. Online Pointer Checker
   Appendix D. Messages and codes
    Messages
  
  The following description in message FPX0061E explanation
  should be removed:
  
   . Possible loop in segment twin chain:
  
  ---------------------------------------------------------------
  The FPX0171W message should be added as follows:
  
     FPX0171W  -> Warning:
     FPX0171W Possible loop in segment twin chain.
     FPX0171W Source   SC seg-code Name seg-name RBA xxxxxxxx
     FPX0171W Target   SC seg-code Name seg-name RBA xxxxxxxx
     FPX0171W Root     SC seg-code Name seg-name RBA xxxxxxxx
     FPX0171W Root key value:
     FPX0171W xxxxxxxxxxxx
     FPX0171W Maximum 255 bytes of contents of source segment:
     FPX0171W xxxxxxxxxxxx
  
     Explanation: OPC detected that the twin segments exceed the
     threshold value, two million, defined by the system.
     OPC assumes that the twin chain may be looped.
  
     System Action: OPC sets an end-of-job return code of 4
     and continues processing, but stops the checking of
     the next twin segment.
  
     User Response: After OPC, run the FABADA3 and FABAD5
     steps and investigate the result that the area actually
     has wrong pointer which may make the twin chain loop,
     or the area has more than two million twin chain.
  
     Issuing Module: FPXAERR0
  210Y
  FPXAERR0
  FPXMBLK
  FPXMBLK0
  FPXMSG00
  FPXNTWN0
  

Temporary fix

Comments

APAR Information

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

  PK25746

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

  UK15090

Modules/Macros

•    FPXAERR0 FPXMBLK  FPXMBLK0 FPXMSG00 FPXNTWN0
  

Fix information

• Fixed component name

  IMS HP FP UTILI

• Fixed component ID

  5655K9400

Applicable component levels

• R210 PSY UK15090

     UP06/06/06 P F606