CICS® VR VSAM batch logging provides logging for your batch changes to VSAM data sets that are not accessed in RLS-mode.
CICS VR forward recovery logging records an after-image log record for every update made to the VSAM data set by a batch job. Therefore allowing you to run CICS VR forward recovery to recover the batch updates if the data set becomes corrupted.
CICSVR undo logging records a copy of the data prior
to any changes being made, so UNDO logging is always done when any
indication is given of intent to update the data, therefore allowing
you to run CICSVR batch backout to remove the batch updates if the
batch job encounter an abend.
If a batch job reads all records using GET UPD commands
even though only a few records are actually updated, CICSVR undo logger
records every before-image record. However, unless a record is updated,
logging the before image is not necessary and it adds to the overhead
and runtime of the batch job. Also batch backout takes longer when
before-images are written back to a dataset but they only replace
identical records. The alternate approach to avoid such overhead is
to specify FRLOG(ALL) for the sphere. In this case, if a subsequent
PUT_UPDATE or ERASE is not done, CICS VR will remove the GET for UPDATE
UNDO record if it is still present in the log buffer
CICS VR replication logging records both the before-image
and the after-image log records in the replication log. If both forward
recovery and replication logging are requested for the VSAM sphere,
the VSAM batch logger shares the forward recovery log for forward
recovery logging and replication logging. If both undo and replication
logging are requested for the VSAM sphere, VSAM batch logger uses
separate logs for undo logging and replication logging.