MTO and tracing operations

The MTO or an authorized remote terminal operator can initiate several kinds of type-1 trace activity with the /TRACE command. Even though you might use the IMS Monitor fairly regularly, you should regard all tracing operations as special requests.

Because trace or monitoring actions affect the performance of the online IMS system, they are not part of normal operations. The validity of the trace depends upon the processing taking place. Also, the operator can control the trace interval with the /TRACE command, so the operator must be aware of the trace timing.

Some types of trace requests do not require the person requesting the trace to be present during normal operations. The request should state the approximate duration of the trace and the type of monitoring. The main section should specify the initial start and termination conditions, as well as any monitoring constraints to be applied. Other sections should prompt for other details, such as queue levels, transactions to be active, or the time of day.

The types of tracing that can be requested are summarized in the following table.

Table 1. Trace and monitor options
Type of trace /TRACE parameters Operational effect
IMS Monitor SET MON opt Initiates IMS Monitor trace.
SET OFF MON Terminates the trace.
opt=ALL Traces all events.
opt=APDB Traces activity between application programs and databases.
opt=APMQ Traces activity between application programs and message queues.
opt=LA Traces line and logical link activity.
opt=SCHD Traces scheduling and termination events.
DL/I Image Capture SET PSB name opt Traces all DL/I calls for the named PSB.
  SET OFF PSB name Terminates the trace.
  opt=COMP Generates PCB and data-compare statement images.
  opt=NOCOMP Generates no compare statement images. Default.
  SET PI OPTION opt Traces program isolation activity, including ENQ, DEQ, and DL/I calls. Trace data is written to system log.
SET PI Traces PI activity. Trace data is kept in storage, and not written to system log.
SET OFF PI Terminates the trace.
opt=LOG Writes trace data to system log. Default.
SET OFF PI OPTION LOG Continues trace, but does not write buffers to system log.
opt=TIME Adds elapsed time for each ENQ and DEQ call when IMS has to wait.
SET OFF PI OPTION TIME Continues trace, but only records time of day.
  opt=ALL Equivalent to opt=LOG TIME.
Line, node, and PTERM tracing SET LINE nn opt Traces line activity.
SET OFF LINE nn Terminates the line trace.
SET NODE nn opt Traces node activity.
SET OFF NODE nn Terminates the node trace.
opt=LEVEL n Sets detail level (1-4) for trace.
opt=MODULE mod Traces modules for IMS communications manager.
mod=DDM Traces device-dependent modules.
mod=MFS Traces MFS modules.
mod=ALL Traces both DDM and MFS modules.
Type-1 Trace Tables SET TABLE opt OPTION LOG Initiates tracing into specified trace tables. IMS writes trace tables to log before reusing them.
SET TABLE opt OPTION NOLOG Initiates tracing into specified trace tables. IMS does not write trace tables to log. Default.
SET OFF TABLE Opt Terminates trace.
opt=ALL Specifies that IMS enable or disable all traces. Default.
opt=DISP Traces dispatching events.
opt=DL/I Traces DL/I calls.
opt=DLOG Traces log activity.
opt=FAST Traces Fast Path activity.
opt=IDC0 Traces errors in modules DFSCNXA0 and DFSIDC00.
opt=LATC Traces latching activity.
opt=LOCK Traces locking and PI activity.
opt=LUMI Traces LU 6.2 and APPC activity.
opt=OTMT Traces OTMA activity.
opt=RETR Traces DL/I retrieve calls.
opt=SCHD Traces scheduling events.
opt=STRG Traces storage manager activity.
opt=SUBS Traces external subsystem events.
Link Tracing for MSC SET LINK nn opt Traces logical link.
SET OFF LINK nn Terminates link trace.
opt=LEVEL n Sets detail level (1-4) for trace.
opt=MODULE mod Traces modules for IMS communications manager.
mod=DDM Traces device-dependent modules.
mod=MFS Traces MFS modules.
mod=ALL Traces both DDM and MFS modules.

IMS can trace several different types of activity concurrently. The IMS Monitor writes its output to a data set specified on the IMSMON DD statement or dynamically allocated. IMS writes other traces to type X'67' log records.