Use the TASKMON Navigation Line Command against an executing STC, SYStem task or Batch Job.
Use the Activity command to display the executing task.
Use the TM Line command against the Jobname.
The Count and Percent columns will show you where the task is spending its time.
The offset column will show you the offset into the module where the STC/JOB is spending its time.
The value in the Offset column will match up to the LIST option of the COBOL compile to find the source code line number.
The TASKMON command monitors the activity of work units within an address space over an interval. This can be used to identify the modules that are being executed and the amount of time spent at different offsets within the modules.