Primary index

Every row in the primary index file has a fixed 77-character length. Each row can represent either one user SYSOUT data set or the three z/OS® SYSOUT data sets together (JESMSGLG, JESJCL, and JESSYSMSG). Each row contains a key showing the job name, job ID, start reader date, and start reader time, that points to the data stored in the data files. To set the right size of VSAM Primary Index file, multiply the average number of SYSOUT data sets per job by the maximum number of jobs stored concurrently in the database. This value is the maximum number of rows in the primary index; it should be increased by an adequate margin to cope with peaks in your workload and to allow for growth.

To find the total space quantity to allocate for VSAM primary index, you should multiply this adjusted maximum row number by the total length of the record.