Secondary index

The secondary index is a variable-length key-sequenced data set (KSDS). Because it can be a single record, that corresponds to a specific secondary-key value, it can trace many primary keys. Currently, a secondary key value is associated to a single primary key only, and, for this reason, each SYSOUT in the secondary index requires one row of 76 characters.

To set the size of the VSAM secondary index file, perform the following steps:
  1. Multiply the average number of SYSOUT data sets for each job by the maximum number of jobs stored currently in the database. The result is the maximum number of rows in the Secondary index.
  2. Increase this value to cope with peaks in workload and to allow for growth.
  3. Multiply this adjusted value by the total length of the record. This gives the total space for allocating for the VSAM secondary index.