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Legac-e - BLKSIZE : Relevance to Performance and Capacity
Inter Block Gaps (IBGs)
This is not a discussion on Fixed (F) length or Variable (V) length record types, but explains the gaps
between the records or blocks of records.
All the data between two IBGs, is governed by the BLKSIZE, and may comprise one or more Logical
Records, the size of which is indicated by the LRECL and RECFM operands.
As the number of IBGs increases, so does the job elapse time. There will also be an increase in CPU usage as each I/O will
use processor handling time.
The next three pages demonstrate the points discussed above.