The component trace service (also referred to in the remainder
of this information as simply “component trace”) provides
common tracing services for components, subsystems, or applications.
Component trace allows you to capture information about application-specific
events for debugging problems in your application, or for system analysis.
To use component trace, you create trace entries at various points
in your application to capture the data you require. You decide the
location of the trace points, what the trace entries will contain,
and which trace entries, if any, to create at any given time. You
store the trace entries in trace buffers. The entries are externalized
in a dump or, by using the component trace external writer, in a trace
data set on a direct access storage device (DASD) or tape.
Benefits of using component trace: While
you might choose to write your own trace services to capture the events,
the advantages of using component trace instead are that you will:
- Have a consistent interface for all application traces.
- Avoid writing duplicate code.
- Eliminate the need to IPL or to use the SPZAP utility to turn
traces on or off; the component trace service allows you to turn
traces on or off dynamically.
- Be able to merge your trace data with other application traces,
IBM-supplied component traces, and GTF user traces.
- Be able to merge different traces from the same system or from
multiple systems in a sysplex.
- Be able to use IPCS to:
- Print or view the trace
- Combine the trace data set with another trace data set
- Extract specific entries from a trace data set
- Merge formatted trace output with other formatted trace output
This information contains the following:
- Planning an application trace tells what you need
to do to establish a component trace for your application, including
how to request it and how to obtain the trace records.
- Coding macros for application traces contains information
about coding component trace macros that enable your application to
use component trace:
- Use the CTRACE macro to do one or more of the following:
- Define your application to component trace
- Delete your application from component trace
- Specify a parmlib member containing trace options
- Define multiple traces for your application
- Indicate that your application supports the component trace external
writer.
- Use the ITTCTE mapping macro when creating trace entries.
- When you are using the external writer:
- Use the CTRACECS macro to manage trace buffers.
- Use the CTRACEWR macro to write your trace buffers to DASD or
tape.
- Coding a start/stop exit routine tells how to write
a component trace start/stop exit routine. You must have a start/stop
routine to use component trace. The start/stop routine starts, stops,
or modifies tracing for the application by controlling the creation
of trace entries by the application.
- Coding a display trace exit routine describes how to write
a component trace display exit routine. The display routine provides
status information about the component trace for the display trace
operator command. This routine is optional.
- Creating trace entries describes how to create
trace entries.