Controlling the sampling interval

You can set the sampling interval for impact analysis collection by selecting the Impact Analysis Settings option (N) on the Control Options path (Main Menu option O) or by entering O.N to fast path to the Workload Impact Analysis Settings panel.

Figure 1. Workload Impact Analysis Settings Panel (O.N)

 ________________ ZCIASET  VTM     CICSSP31 V530./C SP22 11/23/13 15:51:03
> PF1 Help     PF3 Back     PF4 Main Menu     PF7 Up     PF8 Down

> A-RTA On      B-RTA Off    C-RTA Status     D-RTA Intervals    E-RTA Scaling
> F-ONDV On     G-ONDV Off   H-ONDV Status    I-Bottleneck Ctl   J-Wait Reasons
> K-INTR Ctl    L-IANL On    M-IANL Off       N-IANL Settings    O-IANL Groups
> P-Collection  Q-Shutdown   R-RLIM On        S-RLIM Off         T-RLIM Status
  U-SMF Status  V-ATFFilters W-ATF Status     X-ITCAM Status
===============================================================================

>                     WORKLOAD IMPACT ANALYSIS SETTINGS

> IMPORTANT:  To limit impact analysis resource utilization, there is an
> automatic timeout interval.  This interval indicates how long the impact
> analysis collector remains active after an impact analysis request.  If the
> interval elapses, the collector terminates itself, freeing data areas.  The
> next impact analysis request reactivates the collector.

> Set the impact analysis automatic time-out interval by typing the number of
> minutes (0 - 99) to elapse before timeout immediately after IATO.  (0
> specifies no time-out).
 IATO
+       << IA0217 IA collection task times out after 5 minutes >>

> A larger sampling interval will also reduce overhead.  To set a new sampling
> interval, remove the > preceding IAST and enter the value of the time
> interval (in tenths of a second) following IAST.
>IAST
+       << IA0205 The data collector sample time =  .9 seconds <<

> To set a new severity threshold (value below which resource contention data
> will not appear), enter the percentage (0-99) after IATH.  If you enter 0,
> all contenders appear on impact analysis displays.

Scroll to the IAST statement to display or reset the sampling interval to specify how often the impact analysis collector checks the status (execution state) of CICS® regions. By default, CICS regions are checked every .9 seconds, or just slightly more than 66 times per minute. (This interval length is set to an irregular value to avoid accidental synchronization with other system events.)

Smaller sampling intervals provide more data and improve accuracy, but do so at the expense of CPU utilization. Conversely, setting larger intervals reduces the CPU requirements of impact analysis, but can reduce the accuracy of the data.