Logging and journaling
All CICS® system logging and journaling is controlled by the CICS log manager, which uses MVS system logger log streams to store its output.
About this task
- System logging
- CICS maintains a system log to support transaction
backout for recoverable resources. CICS implements
system logging automatically, but you can define the log stream as
DUMMY to inhibit this function. However, if you specify TYPE(DUMMY)
for the system log, you are running without any transaction backout
facilities and without any restart capability, and you can start CICS with
START=INITIAL only.
CICS also supports programming interfaces that enable you to write your own data to the system log, but user-written records should be for recovery purposes only.
- Forward recovery logging
- CICS supports forward recovery logs for VSAM
data sets.
Forward recovery logging is not automatic—you must specify that you want this facility for your files, and also define the forward recovery log streams.
- Autojournaling
- CICS supports
autojournaling of file control data and terminal control messages. Autojournaling is generally used
for audit trails.
Autojournaling is not automatic—you must specify that you want this facility for your files and terminal messages, and also define the general log streams to be used.
See the JOURNAL attribute described in FILE attributes and PROFILE attributes for information about specifying automatic journaling on FILE and PROFILE resource definitions.
- User journaling
- CICS supports
programming interfaces to enable CICS applications to write user-defined records to user journals, which are
held on general log streams.
See Defining CICS general logs for information about defining general log streams for user journals.
Autojournaling and user journals play no part in CICS recovery and therefore are not discussed here.
The CICS log manager writes the data associated with these logging and journaling activities to two types of MVS log stream:
- System log streams
- These are used by the CICS log manager and the CICS recovery manager exclusively for unit of work recovery purposes. Each system log is unique to a CICS region, and must not be merged with any other system log.
- General log streams
- These are used by the CICS log manager for all other types of logging and journaling. You can merge forward recovery records, autojournal records, and user journal records onto the same general log stream, from the same, or from different, CICS regions.
For information on how CICS handles the different error conditions detected by the CICS log manager, see Log manager waits.