General logging guidelines

Both CICS® VR forward recovery logging and undo logging write to MVS system logger log streams.

Both DASD-only log streams and coupling facility log streams, or a combination of both are supported, as described:

DASD-only logging

Use DASD-only log streams when you do not have access to or do not want to use a coupling facility for logging. DASD-only log streams can only be single-system in scope; only one system can connect to a DASD-only log stream.

Coupling facility logging

Use coupling facility logging if you have applications that run on multiple systems in the sysplex and require a single sysplex-wide log stream. A coupling facility is required to merge the data from multiple systems into a single log stream.

Combination of coupling facility logging and DASD-only logging

You can use a combination of coupling facility logging and DASD-only logging if you use a coupling facility. You can have applications that run on multiple systems in the sysplex that require the log records to be merged into a single log stream. You can also have applications that require separate DASD-only log streams for each system. The coupling facility manages both the coupling facility logging and the DASD-only logging in the sysplex.

To help you decide which type of log stream is correct for you, see z/OS® MVS Setting Up a Sysplex. This book also contains detailed information on how to set up the coupling facility resource management policy (CFRM policy) and the LOGR couple data set (LOGR policy).

Any logstream that CICS VR VSAM batch logging writes to is automatically registered in the CICS VR RCDS. Therefore, information about the log streams can be viewed through the CICS VR log stream list of the CICS VR ISPF panel interface.

In addition, a retention period can be specified for all registered log streams. If specified, CICS VR deletes log blocks from all registered log streams that are older than the specified retention period. See Understanding CICS VR automatic deregistration for more information.