IDIS subsystem storage requirements

If using PARM='NOUPDINDEX', then there is no requirement for any REGION size specification—a default 32 MB region is adequate.

If using PARM='UPDINDEX' (this value is the default), then a larger region size should be used. The region size in megabytes can be approximated as follows:
32 + (num_hist_files * (0.5 + (avg_num_entries * 0.0005)))
The total number of PDSE history files that are managed by the IDIS subsystem.
The average number of fault entries in the managed history files.

If a maximum number of fault entries has been set for a history file using the IDIUTIL batch utility SetMaxFaultEntries control statement (for details, see Managing history files (IDIUTIL utility)), then this number is the number of fault entries that should be included for that history file.