Region size requirements for the Initialize function

The Initialize function of FPA operates in a virtual storage region as z/OS® batch job steps. HFPMAIN0 runs in 31-bit addressing mode.

Region size for the Initialize function depends on the size of a UOW, the number of files being initialized, the number of output areas, and the OTASKCTL specification. Typically, database maintenance is a relatively important function. To increase the performance of the initialize program, it would be advisable to run it in a region that has a relatively high dispatching priority (that is, at least equal to the dispatching priority of a message processing region).

Estimating the region size for the Initialize function

The region size required for the Initialize function is a function of the size of a UOW, the number of areas being initialized, the number of output files, and the OTASKCTL specification.

In most cases, the specification on the EXEC statement for HFPMAIN0 of a region that is too small, is detected during the initialization processing of the main task. This causes processing to be terminated at that point. Under certain conditions, the region size shortfall does not become evident until the actual initialization has begun. The job must be completely rerun. Thus, the region size calculations must always be performed prior to initiating initialize processing.

The following worksheet is for estimating the region size that is required for a typical initialize job. The actual region size depends on the keywords that are specified for the job. Therefore, when you specify the region size in your JCL, use a higher value than the value calculated from this worksheet.

Figure 1. Worksheet for estimating region size for the Initialize function
FPA programs, internal tables, control blocks 3,020,000

Number of areas defined in DBD * 1,300        ---------

      Internal tables, control blocks      18,200

      Maximum CISZ * 6                  ---------

                               subtotal ---------

      Value specified on OTASKCTL * subtotal  ---------

      Internal tables, control blocks       3,700

                               subtotal ---------

      Number of initialized areas * subtotal  ---------

Total of CISZ * UOW1 of each area * 2         ---------

Total bytes of initialize storage             ---------