Separating system logger production and test log streams

Starting with z/OS® V1R8, you can separate log streams into two groups, production and test. This means that you can separate system logger processing for test log streams from your production work log streams on a single system. Your production log streams are then protected from a hang or failure in the system logger test environment.

To separate log streams into production and test log streams you can use the GROUP(PRODUCTION | TEST) parameter in the following ways:

To group log streams using a batch program, use the GROUP(PRODUCTION | TEST) parameter on the DEFINE or UPDATE requests on the administrative data utility, IXCMIAPU.
To group log streams using a program, use the new GROUP(PRODUCTION | TEST) parameter on the DEFINE or UPDATE requests on the IXGINVNT service.

When you have log streams separated into production and test groups, system logger will do data set processing, such as data set allocations, data set recalls, and other functions for the two log stream groups in two different sets of tasks. In addition, system logger limits resource consumption of TEST log streams as follows:

TEST log streams are limited to using a maximum of 25% of the connections allowed, while PRODUCTION log streams can use at least 75% of connection slots.
TEST log streams are limited to using a maximum of 25% of LOGR couple data set extents allowed, while PRODUCTION log streams can use at least 75%.

By default, log streams are PRODUCTION log streams. This means that existing log streams with no GROUP designation are PRODUCTION log streams.

Using structures with grouped log streams: A coupling facility structure can only have one type of log stream assigned to it, either TEST or PRODUCTION. If you try to assign a TEST log stream, for example, to a STRUCTURE with PRODUCTION log streams, the request will fail with a reason code of IxgRsnCodeBadGroup (X'08E9').

The first log stream that is defined to a structure determines what type of log streams can be defined to that structure. If the first log stream defined to a structure is a TEST log stream, you can only define TEST log streams to that structure. If you specify or default to PRODUCTION for the first log stream defined to a structure, you can only define other PRODUCTION log streams to that structure.

Other support for separating test and production log streams: The following interfaces support the separation of test and production log streams:

The DISPLAY LOGGER command displays the group designation for log streams. See DISPLAY LOGGER command in z/OS MVS System Commands.
The IXCMIAPU utility LIST LOGSTREAM request displays the group designation for log streams. See LIST LOGSTREAM keywords and parameters.
SMF record type 88, subtype 1, Log Stream section, includes field SMF88GRP to display the group designation for each log stream. See Log Stream section in z/OS MVS System Management Facilities (SMF).
IXGQUERY will return the log stream group designation as long as you specify a large enough buffer length (200 bytes or greater). See IXGQUERY in z/OS MVS Programming: Assembler Services Reference IAR-XCT.
ENF signal 48 for DEFINE and UPDATE log stream requests will identify the group of the log stream.