Region size requirements for the Tune function
The Tune 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 Tune function depends on the size of a UOW, the number of areas to simulate, and the ITASKCTL and OTASKCTL specifications. Typically, database maintenance is a relatively important function. To increase the performance of the tune 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 Tune
The region size required for the Tune function is a function of the size of a UOW, the number of areas being analyzed, and the ITASKCTL and OTASKCTL specifications.
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 tune process has begun. The job must be completely rerun. Thus, the region size calculations must always be performed prior to initiating tune processing.
The sort program also requires storage region. For how to estimate the region size, see the DFSORT Application Programming Guide.
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 the following worksheets.
The following worksheet is for estimating the region size that is required for a typical tune job with the AREASCAN=YES option.
FPA programs, internal tables, control blocks 3,020,000
Number of areas defined in DBD * 1,300 ---------
Maximum Segment length * 1,100 ---------
Internal tables, control blocks 93,000
Storage used by Sort program ---------
(Maximum segment code + 1) * 350 ---------
subtotal ---------
Value specified on ITASKCTL * subtotal ---------
Number of input areas * 4,000 ---------
Total of CISZ * UOW1 of each area * 2 ---------
Total of CI size of each area ---------
Total of X * (126 + MAX Segment Level * 4) ---------
X : Total of maximum number of (RAP/PTF/PCF)
per one UOW in each area
Internal tables, control blocks 50,000 (If CISNAP=YES)
Storage used by Sort program --------- (If CISNAP=YES)
CI size of the area where pointer errors are
detected --------- (If CISNAP=YES)
subtotal --------- (If CISNAP=YES)
Number of areas where pointer errors are detected
* subtotal --------- (If CISNAP=YES)
Storage used by Sort program ---------
Maximum number of UOW in all areas * 100 ---------
Total bytes of tuning storage --------- The following worksheet is for estimating the region size that is required for a typical tune job with AREASCAN=NO.
FPA programs, internal tables, control blocks 1,950,000
Number of areas defined in current DBD * 1,300 ---------
Number of areas defined in simulated DBD * 1,300 ---------
Internal tables, control blocks 19,224
{28 + (the maximum segment level * 4)
+ root key length} * 1000 ---------
subtotal ---------
Value specified on ITASKCTL * subtotal ---------
Internal tables, control blocks 20,824
Storage used by Sort program ---------
34 + (root key kength
+ the maximum segment level * 4) ---------
Number of segments defined in DBD * 19 ---------
Number of DOVF CIs in a UOW * 13 ---------
Number of IOVF CIs * 17 ---------
subtotal ---------
Value specified on OTASKCTL * subtotal ---------
Number of input areas * 4,864 ---------
Number of simulated areas * 4,472 ---------
Maximum number of UOW in all areas * 100 ---------
Total bytes of tuning storage --------- If both AREASCAN=YES and ICACHE=YES are specified and if an image copy data set is used as the input data, the Tune function preloads all image copy records into the data space. The data space size required for the Tune function is a total of the size of the original area data set.
The following figure shows a worksheet for estimating the data space size for the Tune function.
Total size of IOVF parts in all areas ---------- (If input data is IC)
Total of CISZ * UOW1 * (ROOT1 - ROOT2) in each area ---------- (If input data is IC)
Total bytes of a data space storage ----------