Identifying Transaction Suspend by Class in a CICS System
This section describes how to use the Strobe Performance Profile reports produced by Strobe for CICS to analyze a CICS region to obtain information about CICS resources causing transaction delay. System programmers can use these reports to spot resource consumption that can be improved to reduce CICS transaction response time. For a full description of these CICS Region-Level reports, see CICS-Transaction-Profile.
Region-Level Reports
Strobe for CICS provides two levels of activity for an entire CICS region.
- Region Suspend By Class report shows what classes caused suspend and dispatch delay time for a CICS region. The percentage of suspend time caused by each class and the average suspend time per user transaction are reported.
- Region Suspend By Resource within Class report shows, for each suspend class, the resource name and type that accounted for the suspend time reported for the class. The resource name, type, and a function descriptor for the resource are reported. Also provided are the percentage of region suspend time caused by the resource and the average suspend time spent by a transaction in the region due to that resource.
Analyzing Transaction Suspend Time by Class
Within a CICS region, transactions may spend time in a suspended state because of the unavailability of a particular resource. Strobe for CICS records every time a transaction waits for a resource to become available and then aggregates all suspend time caused by the resource to show which ones are most hindering transaction performance. This information can be used by the system programmer to find classes of resources for which access needs to be improved.
Suspend by Class Report
The Suspend by Class report shows how a transaction region is affected by suspend and dispatch delay time during a Strobe measurement session. There are two columns of measurement data:
PERCENT OF REGION SUSPEND
This column shows a percentage of aggregate wait for each suspend class in proportion to the total wait time for the CICS region.
AVERAGE TX SUSPEND TIME
This column reports in seconds the average time that a user transaction running in the region was suspended due to a particular class of resources.
The FILE CONTROL class in the following figure shows a suspend percentage of 97.02%, which indicates that transactions’ attempts to access files could be causing excessive contention. The next report to examine shows specifically what is causing file control contention.
Region Suspend by Class Report
Region Suspended by Resource Within Class Report
The Region Suspended by Resource Within Class report (Region Suspended by Resource Within Class Report) shows, by class, what resource type and name caused suspend time within the region. Each suspend class contained in the Region Suspend by Class report is broken down by the resources causing the suspend time. If none of the resources within a class meets the specified threshold, the entire class is suppressed. If none of the resources meets the specified threshold, the entire report is suppressed.
For each resource type within a class, the resource type, name, and function descriptor is provided. Each class is listed in the same order as in the Region Suspend by Class report. See CICS API Service Time Report for more information.
Region Suspended by Resource Within Class Report
In this report example, the FILE CONTROL class caused 97% of the region suspend time and an average transaction suspend time of 153.776 seconds due to resource STDCLCFL. The resource type for STDCLCFL is FCPSWAIT. The function descriptor for FCPSWAIT is WAIT FOR VSAM STRING. If you find that tasks frequently wait on this resource type, you can try to lower buffer wait by increasing the number of VSAM strings in the FILE resource definition. Refer to IBM’s CICS Problem Determination Guide for more information about resource types and suggestions for improving CICS code.