OA61271: NEW FUNCTION - BSAM SUPPORT FOR BYPASS EXTENT CHECK

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• New Function
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All users of z/OS wishing to exploit the Bypass Extent Check *
  * feature of IBM Enterprise Disk                               *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * New Function.                                                *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  

Problem conclusion

• The following updates will be reflected in a future revision
  of z/OS DFSMS Macro Instructions for Data Sets (SC23-6852-XX):
  
  Chapter 5. Non-VSAM macro descriptions
  DCBE ?(BDAM, BSAM, QSAM, BPAM and EXCP)
  
  The format of the DCBE macro is:
  [label]	DCBE	[,BLKSIZE=n]
  				[,BLOCKTOKENSIZE={LARGE|SMALL}]
  				[,BYPASS_AUTH={NO|YES}]
                                  [,BYPASS_EXTENT_CHECK={NO|YES}
  				[,CAPACITYMODE=XCAP]
  				[,CONCURRENTRW=({YES[,{EXTLOCK|TRKLOCK}]|NO})]
  				[,EADSCB=OK|NOTOK]
  				[,EODAD=relexp]
  				[,FIXED=USER]
  				[,GETSIZE={YES|NO}]
  				[,HYPERWRITE={YES|NO}]
  				[,LOC={ANY|BELOW}]
  				[,MULTACC=n]
  				[,MULTSDN=n]
  				[,NOVER={YES|NO}]
  				[,PASTEOD={YES|NO}]
  				[,RMODE31={BUFF|NONE}]
  				[,SYNAD=relexp]
  				[,SYNC={SYSTEM|NONE|(NUMFILES,nnn)}]
  
  BYPASS_EXTENT_CHECK={YES,NO}
  Specifies the user request for Bypass Extent Check,
  which may result in better performance when multiple
  applications are simultaneously reading and/or writing
  the same disk extent ranges. Caller must be APF authorized,
  running in supervisor state or system key.
  If the associated data set is not an extended format
  data set this parameter will be ignored.
  
  Normally when your program writes on DASD, the DASD subsystem
  performs extent serialization, which prevents all access to
  that extent from all other programs on all systems while
  data is being written.  This prevents other programs
  from reading and writing within the extent and seeing
  certain types of incomplete updates.
  If you know that other programs might be reading the
  data set at the same time that your program is writing,
  and a mechanism exists within those other programs
  to avoid or tolerate potentially incomplete updates
  within an extent, then coding BYPASS_EXTENT_CHECK=YES
  might give better performance. This improved performance
  is due to the DASD subsystem serializing access to only
  one track at a time, not to the whole extent.
  No matter what you code for the BYPASS_EXTENT_CHECK
  keyword, your program will always see consistent data
  within each track.  Note that failure to provide the
  proper protection when specifying this option may result
  in corrupted data.
  

Temporary fix

Comments

APAR Information

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

  OA60658

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

  UJ05362

Modules/Macros

• IHADCBE  DCBE     DCBEP    IGGSSCB  IGG0193W
  

Fix information

• Fixed component name

  BASE ACCESS MET

• Fixed component ID

  5695DF102

Applicable component levels

• R250 PSY UJ05362

     UP21/05/04 P F105

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.