IBM SC34-7012-01 manual Basic direct access method BDAM, Defining files as recoverable resources

Forward recovery

For VSAM files, you can use a forward recovery utility, such as CICSVR, when online backout processing has failed as a result of some physical damage to the data set. For forward recovery:

vCreate backup copies of data sets.

vRecord after-images of file changes in a forward recovery stream. CICS does this for you automatically if you specify that you want forward recovery support for the file.

vWrite a job to run a forward recovery utility, and keep control of backup data sets and log streams that might be needed as input. CICSVR automatically constructs the forward recovery job for you, using an ISPF dialog interface.

Backward recovery

To ensure that VSAM files can be backward recoverable, you must consider the following points:

vKey-sequenced data sets (KSDS) and both fixed- and variable-length relative record data sets (RRDS):

–If the files referring to KSDS or RRDS data sets are designated as recoverable with LOG(ALL) specified, CICS can back out any updates, additions, and deletions made by an interrupted unit of work.

–For information about backout failures, see “Backout-failed recovery” on page 79.

vEntry-sequenced data sets (VSAM-ESDS):

–New records are added to the end of a VSAM-ESDS. After they have been added, records cannot be physically deleted. A logical deletion can be made only by modifying data in the record; for example, by flagging the record with a “logically deleted” flag, using an XFCLDEL global user exit program.

See “Transaction backout” on page 74 for more information.

Basic direct access method (BDAM)

CICS does not support forward recovery for BDAM files. You can implement your own forward recovery support using automatic journaling options.

Backout for BDAM data sets is the same as for ESDS data sets in that you cannot delete records from the data set.

Defining files as recoverable resources

This section describes how to define the recovery attributes for files managed by

CICS file control.

About this task

You specify recovery options, including forward recovery, either in the integrated
catalog facility (ICF) catalog (if you are using DFSMS 1.3 or later), or in the CICS
FILE resource definition, as follows:
v	If your VSAM data sets are accessed by CICS in RLS mode, the recovery
	attributes must be defined in the ICF catalog.
v	If your VSAM data sets are accessed by CICS in non-RLS mode, you can define
	recovery attributes in either the FILE resource or the ICF catalog. If you use the
	ICF catalog to define attributes for data sets accessed in non-RLS mode, CICS

126CICS TS for z/OS 4.1: Recovery and Restart Guide