Planning for channel initiator SMF data

You need to plan the implementation of collecting SMF data for the channel initiator.

The channel initiator produces two types of record:

Statistics data with information about the channel initiator and the tasks within it.
Channel accounting data with information similar to the DISPLAY CHSTATUS command.

You start collecting statistics data using the command:


START TRACE(STAT) CLASS(4)

and stop it using the command:


STOP TRACE(STAT) CLASS(4)

You start collecting accounting data using the command:


START TRACE(ACCTG) CLASS(4)

and stop it using the command:


STOP TRACE(ACCTG) CLASS(4)

You can control which channels have accounting data collected for using the STATCHL attribute on the channel definition or the queue manager.

For client channels, you must set STATCHL at the queue manager level.
For automatically defined cluster sender channels, you can control the collection of accounting data with the STATACLS queue manager attribute.

The default value of STATCHL for the queue manager is OFF. In order to collect channel accounting data you must change the value of STATCHL from the default on either the queue manager or channel definition, in addition to starting class 4 accounting trace.

The SMF records are produced when:

The time interval indicated by the CSQ6SYSP STATIME parameter has elapsed, or if STATIME is zero, on the SMF data collection broadcast. The request to collect SMF data for the channel initiator and the queue manager are synchronized.
A STOP TRACE(ACCTG) CLASS(4) or STOP TRACE(STAT) CLASS(4) command is issued, or
The channel initiator is shut down. At this point any SMF data is written out.

If a channel stops during the SMF interval, accounting data is written to SMF the next time the SMF processing runs. If a client connects, does some work and disconnects, then reconnects and disconnects, there are two sets of channel accounting data produced.

The statistics data normally fits into one SMF record, however, multiple SMF records might be created if a large number of tasks are in use.

Accounting data is gathered for each channel for which it is enabled, and normally fits into one SMF record. However, multiple SMF records might be created if a large number of channels are active.

The cost of collecting the channel initiator SMF data is small. Typically the increase in CPU usage is under a few percent, and often within measurement error.

Before you use this function you need to work with your z/OS® systems programmer to ensure that SMF has the capacity for the additional records, and that they change their processes for extracting SMF records to include the new SMF data.

For channel initiator statistics data, the SMF record type is 115 and sub-type 231.

For channel initiator accounting data, the SMF record type is 116 and sub-type 10.

You can write your own programs to process this data, or use the SupportPac MP1B that contains a program, MQSMF, for printing the data, and creating data in Comma Separated Values (CSV) format suitable for importing into a spread sheet.

If you are experiencing issues with capturing channel initiator SMF data, see Dealing with issues when capturing SMF data for the channel initiator (CHINIT) for further information.