Starting, stopping and changing the trace

Your application can start and stop tracing with or without operator intervention. To start tracing means to start creating the trace entries in the application's code. To stop tracing means to stop creating trace entries, or to revert to the minimum level of tracing. The following are the ways to start, stop and change tracing:

Through the TRACE CT and REPLY operator commands
Through a parmlib member:
- On CTRACE DEFINE
- On the TRACE CT operator command, with or without PRESET.

See Using parmlib members for more information about using parmlib members with component trace.

To start or stop a trace, the system passes control to your start/stop exit routine. Once the exit routine gets control, it can set a flag in the application's control information to indicate that the application should either start or stop tracing.

When you start tracing, either through the operator or through a parmlib member on CTRACE DEFINE, you specify an initial set of trace options. At some point, you might need to change these trace options. If you specify MOD=YES on CTRACE DEFINE, you allow the operator to change the trace options without turning the trace off. If you specify MOD=NO on CTRACE DEFINE (or take the default), the operator must turn the trace off, and then turn the trace back on with the new options.