Parameters specified in the CICS® definitions of VSAM files determine
whether or not autojournaling is to be performed, and the types of operations
(add, read, or others) that are recorded.
The following parameters must be set in the CICS file definitions of every VSAM sphere
that you want CICS VR
to forward recover from log records produced by CICS TS autojournaling. See CICS Resource
Definition Guide for a further explanation of the listed parameters.
- JOURNAL(number)
- Specifies that you want automatic journaling for this file. The journaled
data is in the format of the VSAM record. The data to be journaled is identified
by the JNLADD, JNLREAD, JNLSYNCREAD, JNLSYNCWRITE, and JNLUPDATE attributes. number is
the number that identifies the journal that CICS is to use for the autojournal. CICS journal
names are of the form DFHJnn, where nn is in the range 1 through
99.
Note: - Automatic journaling is independent of logging to the system and forward
recovery logs, as specified by the RECOVERY and FWDRECOVLOG attributes.
- When specifying CICS TS autojournaling for use with CICS VR, the
automatic journaling log stream that is specified must not also be
written to by CICS forward
recovery logging.
- In releases prior to CICS Transaction Server for OS/390® Release 1, DFHJ01 was the system
log, but that is not now the case.
- JNLADD(AFTER)
- Specifies that CICS journals the file control write operation after
the VSAM I/O operation on the journal nominated by the JOURNAL attribute.
- JNLUPDATE(YES)
- Specifies that REWRITE and DELETE operations must be recorded on the journal
nominated by the JOURNAL attribute.
- JNLSYNCWRITE({YES|NO})
- Specifies whether you want the automatic journaling records, which are
written for WRITE operations to the journal specified by JOURNAL, to be written
synchronously or asynchronously.
During forward recovery processing, CICS VR
applies the log records produced by CICS TS autojournaling in the order that
they are listed on the log. If JNLSYNCWRITE is set to NO, log records might
not be written to the log in the correct time sequence. This could cause undesirable
results during forward recovery processing. However, setting JNLSYNCWRITE
to YES might cause some additional overhead to occur during CICS TS autojournaling.
One of the primary reasons to use CICS TS autojournaling instead of CICS forward
recovery logging is the possibility of avoiding some overhead, so this benefit
can be reduced when JNLSYNCWRITE is set to YES.
Note: CICS forward
recovery logging is the recommended logging method for use with CICS VR. However,
if you choose to use log records produced by CICS TS autojournaling for the forward
recovery of VSAM spheres, you must not have CICS forward recovery logging enabled for
the same spheres. Enabling both logging methods for forward recovery purposes
for the same VSAM sphere, could result in duplicate information being stored
in the RCDS, causing unpredictable results during recovery job creation.