CICS XRF tracing

CICS XRF tracing is always active when you are running with XRF. It is used by the CICS availability manager (CAVM), and you cannot turn it off. However, it only makes about 12 entries every 2 seconds, so the overhead is not great. Note that CICS XRF tracing is quite distinct from the "normal" CICS tracing that can originate from the CAVM, which is identified by trace point IDs AP 00C4 through AP 00C7.

The XRF trace entries are 32 bytes long and are written to a trace table in main storage. The table has a fixed size of 64KB, and it wraps around when it is full.

The table starts with 28 bytes of control information, in the format shown in Table 22.

Table 22. Control information at the start of the XRF trace table
Bytes Contents
 0-15 '*** XRF TRACE **'
16-19 Address of start of trace entries
20-23 Address of end of trace entries
24-27 Address of end of most recent entry

Trace entries are 32 bytes long, and have the format shown in Table 23.

Table 23. Format of an XRF trace entry
Bytes Contents
 0 Type code
 1 Subtype
 2-3 Process ID of XRF process that made the entry
 4-27 Trace data--the format depends on the type or the subtype
28-31 Clock value when entry was made, same format as "normal" CICS trace entries

Process IDs are assigned in order of process ATTACH starting from 1. Some special values are used for processes which are not known to the dispatcher, but which cause trace entries to be made. These are:

Process ID Function
X'0000' Initial attach
X'FFFE' ESPIE/ESTAE error handling
X'FFFF' Dispatcher activities.

Entry types

The entries are as follows:

Table 24. XRF trace entry types
Module Type Subtype Description
DFHWLGET 1 1 Module entry
Bytes 4-11 Module name
Bytes 12-15 LIFO allocation address
DFHWLFRE 1 2 Module return
Bytes 4-11 Module name
Bytes 12-15 LIFO allocation address
Bytes 16-27 0
DFHWDATT 2 1 XRF process attach
Bytes 4- 7 Process entry point
Bytes 8-11 Initial data parameter
Bytes 12-15 Address of ESPIE routine
Bytes 16-19 Address of ESTAE routine
Bytes 20-23 Address of attached process XPB
Bytes 24-27 Process ID attached process XPB
DFHWDISP 2 2 XRF process detach
Bytes 4-27 0
DFHWDISP 2 3 XRF process dispatch
Bytes 4- 7 Address of external ECB waited for
Bytes 8-11 Address of internal ECB waited for
Bytes 12-15 Awaited broadcast events which were posted
Bytes 16-19 Broadcast events still posted for this process
Bytes 20-23 Address of process XPB
Bytes 24-27 Locks held by this process
DFHWDWAT 2 4 XRF process wait (event data)
Bytes 4- 7 Address of external ECB to wait for
Bytes 8-11 Address of internal ECB to wait for
Bytes 12-15 Broadcast events to wait for
Bytes 16-19 Events to be broadcast to all processes
Bytes 20-23 Events to be reset for this process
Bytes 24-27 0
DFHWDAT 2 5 XRF process wait (lock data)
Bytes 4- 7 Locks to be freed
Bytes 8-11 Locks to be acquired
Bytes 12-19 0
Bytes 20-23 Locks held by all other processes at time of call
Bytes 24-27 Locks held by this process at time of call
DFHWDISP 2 6 Dispatcher termination
Bytes 4-27 0
DFHDISP 2 7 Dispatcher issuing OS WAIT
Bytes 4-19 0
Bytes 20-23 Address of WAIT list
Bytes 24-27 Number of ECBs in WAIT list
DFHWDISP 2 8 Dispatcher resume after OS WAIT
Bytes 4-27 0
DFHWMMT 3 1 Message manager issuing VSAM GET
Bytes 4- 7 RPL address
Bytes 8-11 RBA of CI to be read
Bytes 12-27 0
DFHWMMT 3 2 Message manager issuing VSAM PUT
Bytes 4- 7 RPL address
Bytes 8-11 RBA of CI to be read
Bytes 12-27 0
DFHWMMT 3 3 Message manager I/O complete
Bytes 4- 7 RPL address
Bytes 8-11 RBA of CI to be read
Byte 12 0
Bytes 13-15 VSAM feedback information
Bytes 16-27 0
DFHWMQH 4 1 Message manager message received
Bytes 4- 7 0
Bytes 8-11 Queue name
Bytes 12-15 Message sequence number
Bytes 16-19 Address of message block (contains message copy)
Bytes 20-27 0
DFHWMWR 4 2 Message manager message sent
Bytes 4- 7 0
Bytes 8-11 Queue name
Bytes 12-15 Message sequence number
Bytes 16-19 Message file cycle number(contains message copy)
Bytes 20-23 RBA of this message
Bytes 24-25 0
Bytes 26-27 Response to PUTMSG request (WMSRESP)

Related Concepts
CICS tracing
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