System Management Facilities (SMF) considerations
If you use SMF data to account for resource consumption, you might need to combine SMF data for accurate information when Subzero redirection occurs.
When a client address space (such as CICS) requests a connection to a target subsystem, Subzero starts a subsystem server address space on the target LPAR. This subsystem server is dedicated to processing requests from that client; a one-to-one relationship exists between the client address space and the subsystem server that Subzero starts on behalf of that client.
While initializing the server, Subzero propagates all Workload Manager (WLM) job accounting, performance monitoring, delay monitoring, and classification data from its associated client address space.
SMF data that z/OS generates for a Subzero subsystem server mirrors the SMF data of the client address space. For example, SMF 30 job accounting records for the subsystem server contain the same accounting information as the records for the client address space. However, the performance and resource data are specific to the subsystem server.
SMF data in an environment with CICS and DB2
When CICS monitoring is enabled, CICS generates SMF 110 records. In a Subzero environment, the SMF 110 subtype 1 record understates CPU utilization for DB2 activity.
In a locally connected CICS and DB2 environment in which Subzero is not active, the DB2 Open Thread Environment (OTE) charges its time directly back to the CICS task control block (TCB). (OTE is available with CICS Version 2.2 and DB2 Version 6 and later.) As a result, CICS generates SMF 110 subtype 1 records that reflect the total CICS and DB2 CPU time.
In a remotely connected CICS and DB2 environment in which Subzero is active, the CICS TCB is suspended while the remote database access request is processed. Because no direct connection exists to the DB2 thread, CICS generates SMF 110 subtype 1 records that reflect only the CICS CPU time and no DB2 CPU time. However, Subzero passes the CICS Correlator ID to DB2. This action allows DB2 to generate the SMF 101 record with the required data for matching that record with the SMF 110 record that CICS produces.
For accurate accounting and capacity management reporting, you will need to combine the SMF 101 data produced by DB2 with the SMF 110 data produced by CICS.
SMF data in a CICS and IMS environment
In a locally connected CICS and IMS environment in which Subzero is not active, IMS passes statistical information for each PSB scheduled and unscheduled interval. CICS provides this information to various exits and maintains internal statistics for downstream reporting.
In a remotely connected CICS and IMS environment in which Subzero is active, Subzero passes this statistical information from the remote IMS system to its client CICS region; this approach allows CICS and all of its exits and downstream reporting to function normally.
If the appropriate PTFs are applied, MainView for IMS generates the FA and F9 IMS log records with the proper IMS accounting and performance data.