Planning for channel initiator SMF data

You need to plan the implementation of SMF data for the channel initiator (CHINIT).

The CHINIT produces two types of record:
  • Statistics data with information about the CHINIT and the tasks within it.
  • Channel accounting data with information similar to the DIS CHSTATUS command.
You start collecting statistics data using: 

/CPF START TRACE(STAT) class(4)
and stop it using 

/CPF STOP TRACE(STAT) class(4)
You start collecting accounting data using: 

/CPF START TRACE(ACCTG) class(4)
and stop it using 

/CPF STOP TRACE(ACCTG) class(4)
The SMF records are produced when:
  • The time interval in the STATIME ZPARM parameter has elapsed, or if STATIME is zero, on the SMF broadcast. The request to collect SMF data for the CHINIT and the queue manager are synchronized.
  • A STOP TRACE(ACCTG) CLASS(4) or STOP TRACE(STAT) CLASS(4) command is issued, or
  • When the CHINIT is shut down. At this point any SMF is written out.
The statistics SMF 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 (using the STATCHL attribute) and normally fits into one SMF record. However, multiple SMF records might be created if a large number of channels are active.

If a channel stops in the 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.

You can control which channels have information written to SMF:
  1. By using the STATCHL option on the channel and queue manager.
  2. For client channels, note that, you must set STATCHL at the queue manager level.
  3. For automatically defined cluster sender channels, you must set STATACLS.

The cost of using the CHINIT 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 CHINIT statistics the SMF record type is 115 and sub-type 231.

For CHINIT accounting 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) 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.