PM71502: MFS REVERSAL UTILITY HAS PERFORMANCE PROBLEM WHEN PROCESSING A LARGE FORMAT LIBRARY

Obtain the fix for this APAR.

APAR status

• Closed as unreproducible in next release.

Error description

• When the MFS reversal utility runs against a large FORMAT
  library with tens of thousands of members, the utility can take
  several minutes to run.
  
  Most of the time is spent generating the cross-reference
  report, which is the default action.
  
  Currently the only way to improve the performance of the utility
  is to choose the NOXRPT option to bypass creation of the report.
  

Local fix

• The performance problem is caused by a module which generates
  cross-reference(XREF) report in the SYSPRINT DD when the format
  library has large number of members.
  
  MFS Reversal provides an option "OPTION NOXRPT" to suppress the
  creation and printing of the cross-reference report.
  
  When the option is specified, the BLDL/FIND SVCs in the module
  which causes the performance problem are not used.
  
  Note: This option also suppresses a warning message to notify
  MFS library members in the format library that refer to the same
  format name as the selected member.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: IMS Library Integrity Utilities for z/OS,    *
  *                 Version 2 Release 1 (FMID=H27P210) users who *
  *                 use the MFS Reversal utility.                *
  ****************************************************************
  * PROBLEM DESCRIPTION: MFS Reversal utility spends much time   *
  *                      to generate MFS source of some members  *
  *                      in a FORMAT library when the FORMAT     *
  *                      library has a large number of members   *
  *                      without OPTION NOXRPT specified.        *
  ****************************************************************
  * RECOMMENDATION: Apply the maintenance for this APAR.         *
  ****************************************************************
  MFS Reversal utility spends much time to generate MFS source of
  some members in a FORMAT library when both of the following
  conditions met:
  
   - The FORMAT library has a large number of members
   - The OPTION NOXRPT is not specified in the SYSIN data set
  
  It takes several minutes to generate MFS source of the selected
  members even if a few members are selected.
  
  When the OPTION NOXRPT is not specified, MFS Reversal utility
  generates the cross reference report and issues a warning
  message to notify FORMAT library members that refer to the same
  format name as the selected members to generate MFS source.
  
  To search the members to be notified in the warning message, MFS
  Reversal utility issues BLDL macro for each member in the FORMAT
  library. If the number of members in the FORMAT library
  increases, the number of I/O access by issuing BLDL macro also
  increases. As a result, it spends much time to generate MFS
  source even if a few members are selected to be generated.
  
  This APAR changes MFS Reversal utility to reduce the number of
  I/O access for the FORMAT library by caching directory
  information of members once read. It can reduce most of
  execution time when generating MFS source of some members from a
  FORMAT library which has a large number of members without
  OPTION NOXRPT specified.
  

Problem conclusion

Temporary fix

Comments

• This APAR improves performance of MFS Reversal utility when
  generating MFS source of some members from a FORMAT library
  which has a large number of members without OPTION NOXRPT
  specified.
  
  Note: After applying this APAR, the storage usage above 16M
  increases by 4Kbyte per 1024 members in the FORMAT library.
  
  The following modules have been modified.
  
  FABVCNTL, FABVDIRC, FABVXRPT
  

APAR Information

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

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

  UK81747

Modules/Macros

• FABVCNTL FABVDIRC FABVXRPT
  

Fix information

• Fixed component name

  IMS LIBR INTEG

• Fixed component ID

  5655I4200

Applicable component levels

• R210 PSY UK81747

     UP12/09/15 P F209

Fix is available

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