CICS logging and journaling

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. System logging is implemented by CICS TS automatically, but you can define the log stream as DUMMY to inhibit the function. If you specify TYPE(DUMMY) for the system log, CICS TS runs without any transaction backout facilities and without any restart capability.

Forward Recovery Logging: CICS supports forward recovery logs for VSAM data sets. A forward recovery log is a general log stream managed by the MVS system logger. CICS writes the after images of changes made to a data set to a forward recovery log. 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. You must specify this information in the ICF catalog if you want RLS mode; if you do not want RLS mode, you can specify this information in either the file resource definition or ICF catalog.

Autojournaling: CICS supports autojournaling of file control data and terminal control messages. Autojournaling is generally used for audit trails. CICS VR can forward recover a VSAM data set from log records produced by CICS TS autojournaling. However, IBM® recommends only using log records produced by CICS TS forward recovery logging with CICS VR. More information about autojournaling can be found in Using CICS TS autojournaling.

User journaling: CICS supports programming interfaces to let CICS applications write user-defined records to user journals, which are held on general log streams. CICS VR does not support forward recovery of a CICS TS VSAM data set using a user journal.

Note: User journals play no part in VSAM recovery.

The CICS log manager writes the data associated with these logging and journaling activities to MVS log streams, which the log manager controls as two types of log streams:

System log streams: These are used by the CICS log manager and the CICS recovery manager for unit of work (UOW) recovery purposes. Each system log is unique to a CICS region and cannot 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.