The CICSVR_UNDOLOG_CONTROL parameter in the active
IGDSMSxx member of SYS1.PARMLIB is used to enable or disable CICS® VR undo
logging on the system, specify the action that CICS VR must take if an undo logging failure
occurs, and specify if CICS VR must perform synchronous undo logging.
The following values can be specified for the CICSVR_UNDOLOG_CONTROL parameter
in the active IGDSMSxx member:
- ENABLE CONT
- Enable CICS VR
undo logging and allow a client application, batch job, to continue execution
when an error occurs with the undo log stream. VSAM sphere updates are not
synchronized with CICS VR undo logging. ENABLE CONT is the default value
for the CICS VR
undo logging control string.
- ENABLE TERM
- Enable CICS VR
undo logging and cancel a client application, batch job, in the case that
an error is encountered with the undo log stream. VSAM sphere updates are
not synchronized with CICS VR undo logging.
- ENABLE SYNC
- Enable CICS VR
undo logging and cancel a client application, batch job, in the case that
an error is encountered with the undo log stream. VSAM sphere updates are
synchronized with CICS VR undo logging.
- DISABLE
- Disable CICS VR
undo logging on the system.
Note: If an undo logging error occurs, but the log stream is still accessible,
for example; the log structure becomes full, you might want to immediately
cancel the batch job, and remove all updates made by the step that was in
progress when the logging error occurred. However, you can perform a successful
batch backout only when ENABLE SYNC has been specified. SYNC verifies that
every log record is successfully written to the undo log stream before control
returns to VSAM.
If SYNC was not specified, and a undo logging error occurs,
then it might be possible that one or more updates have been made to VSAM
data sets that are not reflected in the undo log stream. In this scenario,
you would need to restore the affected VSAM spheres from a backup and either
run forward recovery or rerun the relevant transactions.
Specifying
SYNC could greatly increase the overhead processing of the batch jobs, and
might not be ideal in all environments.
- Examples
-
- CICSVR_UNDOLOG_CONTROL(ENABLE CONT)
- Enable CICS VR
undo logging for all VSAM spheres defined with FRLOG ALL or UNDO and allow
a client application, batch job, to continue when a logging error occurs.
The VSAM sphere updates are not synchronized with CICS VR undo logging.
- CICSVR_UNDOLOG_CONTROL(DISABLE)
- Disable CICS VR
undo logging. No undo logging is performed regardless of the FRLOG settings
for the VSAM spheres.