Self-defining sections

Use this topic as a reference for format of the self-defining sections of the SMF record.

A self-defining section of a type 115 SMF record tells you where to find a statistics record, how long it is, and how many times that type of record is repeated (with different values). The self-defining sections follow the header, at fixed offsets from the start of the SMF record. Each statistics record can be identified by an eye-catcher string.

The following types of self-defining section are available to users for type 115 records. Each self-defining section points to statistics data related to one of the IBM MQ components. Table 1 summarizes the sources of the statistics, the eye-catcher strings, and the offsets of the self-defining sections from the start of the SMF record header.

Source of statistics Record subtype (SM115STF) Offset of self-defining section Eye-catcher of data
Dec Hex
Storage manager 1 100 X'64' QSST
Log manager 1 116 X'74' QJST
Message manager 2 36 X'24' QMST
Data manager 2 44 X'2C' QIST
No longer used. The self-defining section will be binary zeros. 2 52 X'34'  
Lock manager 2 60 X'3C' QLST
Db2 manager 2 68 X'44' Q5ST
Coupling Facility manager 2 76 X'4C' QEST
Topic manager 2 84 X'54' QTST
SMDS usage 2 92 X'5C' QESD
Buffer manager - one for each buffer pool 215 36 X'24' QPST
Channel initiator 231     QWSX
Data manager page set - one for each page set 201 36 X'24' QIS1
Storage manager 5 36 X'24' QSPH
Storage manager 6 36 X'24' QSGM
Storage manager 7 36 X'24' QSRS
Note: Some of the storage manager information in subtype 5, 6 and 7 records is intended only for IBM use. Other self-defining sections that are not listed contain data for IBM use only. Each self-defining section is two fullwords long and has this format:
ssssssssllllnnnn
where:

  • ssssssss is a fullword containing the offset from the start of the SMF record.
  • llll is a halfword giving the length of this data record.
  • nnnn is a halfword giving the number of data records in this SMF record.

For more information see, Examples of SMF statistics records.

Note: Always use offsets in the self-defining sections to locate the statistics records. Parent topic: Interpreting IBM MQ for z/OS performance statistics