How do you know if you have to just increase the indexing capacity, or if you have to increase the allocation size of the FILES Data Set?
The FILES Data Set Status Report has the information you need to manage the size and capacity of the FILES.
(Systems Guide, Chapter 2: Files Data Set Management)
Run the status report periodically.
There are two capacities to be aware of:
The Physical Capacity - pertains to the size of the allocation of the FILES.
The Logical Capacity - pertains to the indexing capacity of the subfiles.
The Physical Capacity is noted in the upper right hand corner of the report.
This shows the Total Blocks allocated and the Blocks Remaining.
If the Blocks Remaining gets down to about 10% of the Total, it is time to plan when to allocate a larger FILES Data Set.
The Logical Capacity of the subfiles is shown in the field MAXIMUM RECORDS.
The only subfile that is likley to be of concern is the DSNINDEX subfile.
The rule here is that the MAXIMUM RECORDS must be MORE than double (triple of possible) than the RECORD COUNT.
If the RECORD COUNT is getting close to half of the MAXIMUM RECORDS, then you should increase the Capacity amount for the DSNINDEX subfile in the FILEDEFN member in parmlib.
If your status report indicates that the DSNINDEX subfile is in OVERFLOW BLOCKS, you must plan to do a REORG of the FILES Data Set.
Click this link to download a FILES Data Set Tutorial that will give you all the information you need to manage the FILES Data Set, the BDAM format.