Defining the coupling facility

It may be difficult to size the SYSZWLM_WORKUNIT structure at first, as there is no sure way to know exactly how many parallel units-of-work may exist at any given time. The best option is take a best guess at the initial and maximum sizes and then alter the structure size based on performance and/or change in demand.

If the structure's maximum size is defined too low, work managers will experience failures when they try to export enclaves. It is the work manager's responsibility to respond to such a failure. The work requests may instead be run locally (increasing the response time), or the work requests may fail.

The best way to estimate the storage size needed is to use the CFSIZER tool, which you can find at Coupling Facility sizer.

Alternately, there are formulas in PR/SM Planning Guide to help estimate the storage size needed. As shown in Table 1, the TDEC value is the estimated number of concurrently executing parallel units-of-work. Use the TDEC estimate along with the other values explicitly given in the table, as follows:

Table 1. Values to use in storage estimation formulas
Value	Description	Specify:
TDEC	Total directory entry count — the maximum number of concurrently executing parallel units of work	Best estimate
TDAEC	Total data area element count	TDEC X 2
MSC	Maximum number of storage classes	1
MCC	Maximum number of castout classes	1
MDAS	Maximum number of data area elements associated with a directory entry	32
DAEX	Data area element characteristic	3
AAI	Adjunct assignment indicator	0
R_de/R_data	Directory to data ratio	1/2

Once you have estimated the initial and maximum sizes for the SYSZWLM_WORKUNIT structure, define the structure as described in z/OS MVS Setting Up a Sysplex. Keep the following points in mind:

WLM requests a coupling facility with “default” connectivity.
Non-volatility is not required.
The coupling facility control code must be at CFLEVEL 9 or higher.

The following sample JCL shows the definition of a SYSZWLM_WORKUNIT structure:

//POLICYX  JOB ...
//STEP1    EXEC PGM=IXCMIAPU
//SYSPRINT DD   SYSOUT=A
//SYSIN    DD   *

   DATA TYPE(CFRM) REPORT(YES)

   DEFINE POLICY NAME(POLICY1) REPLACE(YES)

     CF   NAME(FACIL01)
          TYPE(123456)
          MFG(IBM)
          PLANT(02)
          SEQUENCE(123456789012)
          PARTITION(1)
          CPCID(00)
          SIDE(0)
          DUMPSPACE(2000)

     CF   NAME(FACIL02)
          TYPE(123456)
          MFG(IBM)
          PLANT(02)
          SEQUENCE(123456789012)
          PARTITION(2)
          CPCID(00)
          SIDE(1)
          DUMPSPACE(2000)

     STRUCTURE   NAME(SYSZWLM_WORKUNIT)
                 SIZE(4000)
                 INITSIZE(3328)
                 PREFLIST(FACIL02,FACIL01)