No detectable additional cost was associated with switching
on CICS® IA data collection,
with all collection options set to N.
Table 1 shows
the CPU cost in microseconds of collecting affinity data for some CICS commands.
Table 1. CPU cost of collecting affinity data for
some CICS commands, in microsecondsAPI command |
Category |
CPU cost with category option set to Y |
ENQ and DEQ |
ENQ, DEQ |
9.2 (see note 1) |
READQ TS |
TS QUEUE |
4.3 |
INQUIRE |
INQUIRE, SET |
3.4 |
POST and WAIT |
WAIT |
4.8 (see note 2) |
Note: - The 9.2 microseconds CICS IA
cost of an ENQ followed by a DEQ is the total CICS IA affinity collector overhead for the
two CICS commands.
- The 4.8 microseconds CICS IA
cost of a POST followed by a WAIT EVENT is the total CICS IA affinity collector overhead for the
two CICS commands.
Affinity exits
There is an important difference
between enabling CICS IA exits
for interdependency and for affinity data collection.
- For interdependency data collection, if a single option is set
to Y or D on the CICS Resources Options panel,
exits associated with that option only are enabled.
- For affinity data collection, if a single inter-transaction or
transaction-system option is set to Y on the CICS Affinities
Options panel, all the affinity data collection exits
are enabled.
So, for example, if only the COLLECT STATS option is set
to Y for affinity data collection, the XEIOUT exit is enabled, and
this exit is driven for every CICS command
encountered. Therefore, a performance overhead is associated with
driving this exit, although no CICS IA
data is collected by this exit.
See CICS IA exits for further details.