Defining system and general log streams

This section describes the definition of system and general log streams under the following headings:

All CICS® system logging and journaling is controlled by the CICS log manager, which uses MVS™ system logger log streams to store its output.

CICS logging and journaling can be divided into four broad types of activity:

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.

See Defining system log streams.

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.

See Defining 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 under file definition attributes and profile definition 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 the CICS System Definition Guide 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:

1. 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.
2. 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 the CICS Problem Determination Guide.

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