CA Dynam for VSE User Guide

Changing File Characteristics
old block size = 800
old record format = FB
CA Dynam/FI calculates the new block size as follows:
new block size = 800/80 X 50
−
new block size = 500
Old format was not fixed, then block size is rounded down to nearest
multiple of record length. (If the block size is less than record length,
record length is used.)
For example, if you specify RECFM=FB and LRECL=80 when:
old record format = VB
(Record length does not apply for variable records.)
old block size = 850
CA Dynam/FI calculates the new block size as follows:
The block size value of 850 is rounded down to the next even multiple
of the LRECL. Thus, new block size = 800.
• If record format is to be:
−
−
Variable-unblocked, then block size equals record length + 4 bytes for
the block descriptor word (BDW)
Variable-blocked and old format (as defined in the program) is fixed or
undefined, then block size equals old blocking factor (old BLKSIZE
divided by old LRECL) multiplied by new record length + 4 bytes for
BDW.
For example, if you specify RECFM=VB when:
old logical record length = 80
old block size = 800
old record format = FB
CA Dynam/FI calculates the new LRECL to be 84 (going from Fixed to
Variable, new LRECL = old LRECL + 4), and the block size is calculated
as follows:
new block size = 800/80 X 84 + 4
new block size = 10 X 84 + 4
new block size = 844
Chapter 6: Controlling File Independence 6–23