XCF_CF_MEMORY_UTILIZATION

Description:

The check raises an exception when a coupling facility reaches the memory utilization percentage threshold defined for the check. Efficient and planned coupling facility memory utilization prevents a CF from becoming over-full and thereby allows the CF to allocate new structures, expand structures, sustain a viable failover environment and participate in structure rebuild and reallocation processing when needed. The memory utilization threshold percentage will be accepted as a parameter to the check. Note that XCF, independent from this check, will automatically contract structures to relieve coupling facility resource constraints when a coupling facility as a whole is at or above 90% memory utilization and coupling facility resources are not being used productively by the structures.

This is a local check.

Reason for check:

The percentage of memory use in a coupling facility should not approach an amount high enough to keep it from allocating of new structures or expanding existing structures.

z/OS® releases the check applies to:

z/OS V1R12 and later.

Parameters accepted:

MAXUTILIZATION is a required parameter indicating the threshold percentage that the Coupling Facility memory utilization should not exceed. The number must be an integer in the range of 1 to 99. Specifying a percent (%) sign is optional (e.g. MAXUTILIZATION(60%)).

It is possible that system-initiated alter processing for a structure may start and increase the memory utilization percentage for a coupling facility before the check executes or raises an exception. This check may issue an exception during reconfiguration actions or during maintenance windows when the percentage of memory use exceeds the specified check parameter.

User override of IBM® values:

The following shows the default keywords for the check, which you can override on either a POLICY statement in the HZSPRMxx parmlib member or on a MODIFY command. This statement may be copied and modified to override the check defaults:

UPDATE CHECK(IBMXCF,XCF_CF_MEMORY_UTILIZATION)
       SEVERITY(MED) INTERVAL(001:00) DATE (20090707)
       PARM(‘MAXUTILIZATION(60)’)
       REASON('Your reason for making the update.')

Reference:

For more information, see z/OS MVS Setting Up a Sysplex.

Messages:

This check issues the following exception messages:

IXCH0456E

See the IXCH messages in z/OS MVS System Messages, Vol 10 (IXC-IZP).

SECLABEL recommended for MLS users:

SYSLOW