The following ECS structure information should be included in the IXCMIAPU job that formats the couple data set containing the Coupling Facility Resource Manager (CFRM) policy:

Name:

SYSIGGCAS_ECS

Size:

Use the following parameters to determine the maximum structure size. See the ES/9000 Processor Resource/Systems Manager Planning Guide for the algorithms that use these parameters to estimate the size of the cache structure. You can also use the CFSIZER to determine how large the structure should be and to generate the JCL. CFSIZER is available at the following website: www.ibm.com/s390/pso/

• Total directory entry count (TDEC): The expected total number of ECS-active catalogs in the sysplex at any one time plus 25%. The 25% is a recommended buffer so that the structure never becomes full. If it does, then the CF default algorithm of reclaiming the least-recently-used entries will take effect. If the structure ever does become full, either catalogs will not be activated or a performance degradation will be experienced for some catalogs because of the overhead involved in rebuilding entries that were reclaimed. The maximum number of ECS-active catalogs that are supported on any one system is 1024.
• Total data area element count (TDAEC): Same as TDEC
• Maximum storage class (MSC): 1
• Maximum castout class (MCC): 1
• Maximum data area size (MDAS): 1
• Data area element characteristic (DAEX): 4
• Adjunct Assignment Indicator (AAI): 0 (zero)
• Directory portion of directory-to-data ratio (R_de): 1
• Data portion of directory-to-data ratio (R_data): 1

The size of the structure must be supplied by the installation in the CFRM policy. (The ECS facility does not specify a size.)

Initial Size:

Since ECS supports dynamic structure size alteration, an initial size (with a buffer smaller than the recommended 25% for the maximum size described above) can be specified in the CFRM policy. See "Managing Coupling Facility Resources" in z/OS MVS Setting Up a Sysplex for information on specifying an initial size.

Preference List:

Determined by the installation. The ECS cache structure does not require a nonvolatile CF.

Exclusion List:

Determined by the installation.