How it works: CICS and IBM z/OS Workload Interaction Correlator

Learn about how CICS uses services provided by IBM® z/OS® Workload Interaction Correlator.

How CICS registers to WIC

CICS uses the IFAWIC service to register to Correlator. When a CICS region starts, it calls the IFAWIC REQUEST=REGISTER service to register the region and request an instrumentation buffer, and provides the CICS WIC exit routine DFHWICEX that SMF calls every 5 seconds during WIC processing.

If the CICS registration is successful, DFHMN0119I and DFHMN0116I messages are issued. CICS then starts collecting data for WIC and listens for ENF event 85.

The CICS® registration will fail due to any of the following reasons, and corresponding messages are issued accordingly:
  • If the CICS system runs on pre-z14 hardware, with APAR PH26768 applied, CICS issues DFHMN0121I; without APAR PH26768, CICS issues DFHMN0118I. CICS will not attempt registration again. IBM z/OS Workload Interaction Correlator is not supported on pre-z14 hardware.
  • If IBM z/OS Workload Interaction Correlator is not enabled in the z/OS system because of the NOWIC option taking effect, DFHMN0122I is issued for CICS systems with APAR PH26768 applied; DFHMN0120I is issued for CICS systems without APAR PH26768.
  • If the z/OS optional, priced feature IBM z/OS Workload Interaction Correlator is disabled, DFHMN0120I is issued. For more information, see IBM z/OS Workload Interaction Correlator: List of base elements and optional features in z/OS.
  • If SMF type 98 subtype 1024 recording is suppressed, DFHMN0120I is issued.

Both DFHMN0122I and DFHMN0120I messages are followed by DFHMN0117I. CICS listens for ENF event 85 before attempting to register again.

  • For any other errors, DFHMN0118I is issued. CICS will not attempt registration again.

When a CICS region terminates, it will be de-registered from WIC implicitly.

What transaction activity data is collected for WIC

CICS collects transaction-level data for each non-system transaction and writes it to a unique slot in the instrumentation buffer.

This means that a slot is associated with one non-system transaction and contains data about completed tasks that were running under that transaction ID.

Up to 255 unique non-system transactions are collected and recorded to a unique slot with their transaction ID, with the rest collected to a catch-all slot with the transaction ID CWIC.

CICS collects the following transaction activity data:
  • Number of tasks per transaction
  • Average response time per task
  • Average CPU time per task
  • CPU time on CP
  • CPU time on z Integrated Information Processor (zIIP)

If the slots in the buffer are filled up, CICS will re-allocate the slots in the buffer to transactions at the next 5-second interval.