Traces record of the processing of a program or transaction. There are six main types of traces on z/OS to assess problems and performance.

System trace

System trace provides an ongoing record of hardware events and software events occurring during system initialization and operation. The system activates system tracing at initialization, which runs continuously, unless your installation has changed the IBM-supplied system tracing. After system initialization, you can use the TRACE command on a console with master authority to customize system tracing. System trace is formatted in a dump using the IPCS SYSTRACE command.

For complete information, see System trace in z/OS MVS Diagnosis: Tools and Service Aids.

Master trace

Master trace maintains a table of all recently issued system messages. This creates a log of external system activity; the other traces log internal system activity. Master trace is activated automatically at system initialization, but you can turn it on or off using the TRACE command. Master Trace is formatted in a dump using the VERBX MTRACE command.

For complete information, see Master trace in z/OS MVS Diagnosis: Tools and Service Aids.

Component trace

The component trace service provides a way for z/OS components to collect problem data about events that occur in the component. Each component that uses the component trace service has set up its trace in a way that provides the unique data needed for the component. Component trace is queried and formatted using the IPCS CTRACE command Trace data is commonly used by the IBM Support Center to:

• Diagnose problems in the component
• Check how the component is running

The IBM support center might direct you to use specific component trace options when you need to recreate a problem to gather more diagnostic data.

For complete information, see Component trace in z/OS MVS Diagnosis: Tools and Service Aids.

Transaction trace

Transaction trace enables you to debug problems by tracing the path of a work unit running in a single system or across systems in a sysplex environment. Transaction trace provides a consolidated trace of key events for the execution path of application or transaction type work units running in a multi-system application environment.

The essential task of transaction trace is to aggregate data showing the flow of work between components in the sysplex that combine to service a transaction. Transaction trace traces events such as component entry, exit, exceptions and major events such as COMMIT, and ROLLBACK.

Restriction: Do not use transaction trace as a component tracing facility.

For complete information, see Transaction trace in z/OS MVS Diagnosis: Tools and Service Aids.

Generalized trace facility (GTF)

GTF traces system and hardware events similar to those in system trace, but also offers the option of an external writer and to write user defined trace events. GTF trace records can be formatted in a dump or trace data set using the IPCS GTFTRACE command.

For complete information, see The Generalized Trace Facility (GTF) in z/OS MVS Diagnosis: Tools and Service Aids.

GFS trace (GFS)

GFS trace is a tool that collects information about the use of the GETMAIN, FREEMAIN, or STORAGE macro. You can use GFS trace to analyze the allocation of virtual storage and identify users of large amounts of virtual storage. You must use the generalized trace facility (GTF) to get the GFS trace data output.

For complete information, see GETMAIN, FREEMAIN, STORAGE (GFS) trace in z/OS MVS Diagnosis: Tools and Service Aids.