Concurrent Manager
Enabling Tracing
Request Level (new in 11i10)
Use the Debug Options button in the Request Submission Form
The profile “Concurrent: Allow Debugging” should be set to “Yes.”
2.Now Click Debug Options button in the Request Submission Form.

3. A new Webpage/browser with following option opens up.

4. Get the Request id for the Concurrent program.
5. Go to the Trace file directory. Search for the file with the Request _id as a part of the file name.(e.g., ls *Request_id*) The file thus got is your Concurrent Program Trace file.
I hope this post will be helpful ,If you have any doubt please let me know