If you use a coupling
facility for your CICS® log streams, define the coupling
facility structures you require for the log streams in your CFRM
policy, in the CFRM data set, and in the LOGR policy, in the LOGR
data set.
Updating the CFRM policy
Coupling facility space is divided into structures using the
coupling facility resource management (CFRM) policy defined in the
CFRM data set. The CFRM policy allows you to define how MVS™ is
to manage coupling facility resources, and you update this policy
using the IXCMIAPU utility. See Figure 1 for
a sample job to define coupling facility structures in the CFRM policy
data set.
Updating the LOGR policy
You define structures in the MVS system
logger LOGR policy in the system logger couple data sets using the
DEFINE STRUCTURE specification of the ICXMIAPU utility. See Figure 2 for a sample job to define coupling
facility structures in the LOGR policy data set.
Before attempting to run any of the IXCMIAPU jobs, ensure
that the MVS system logger, IXGLOGR, is running. If IXGLOGR
is not running, for example, if MVS is
running in LOCAL mode, logstream definition jobs fail with rc=0814.
Multiple log streams can write data to a single coupling facility
structure. The log data is not merged; the log data stays segregated
according to log stream. You can specify the number of log streams
that use the resources of a single coupling facility structure using
the LOGSNUM parameter on the IXCMIAPU service to define a structure.
Each log stream is allocated a proportion of the structure space
based on the number of currently connected log streams, up to the
limit specified in LOGSNUM.
For example, you might define a structure to contain a maximum
of, say, 30 log streams. If only 10 log streams are connected, each
log stream can use one tenth of the space in the structure. As other
log streams are connected and disconnected, the MVS system
logger adjusts the proportion of space to be used by each log stream.
You must plan carefully before specifying a value for LOGSNUM,
because this parameter determines how much storage space in the structure
is available to each log stream. A number in the range 10 to 20 is
optimum in many environments.
The JCL in Figure 2 defines log stream
coupling facility structures to the MVS system
logger. It is meant for guidance only and you must substitute values
appropriate to your requirements.
See the z/OS MVS Programming: Assembler
Services Guide for
information on planning coupling facility configurations.