We are facing the following issue. Sometimes a job just hangs ( does not exit after completion )
which makes other jobs to wait in the queue , until we shutdown and restart the program itself.
What can be done to prevent this from happening ?

Set the job to run detached to physically separate it from the scheduler.

If by itself this doesn't solve the problem create another helper job that will launch this one and then kill it after certain time in cases if it hangs. You can use RunAndWait "24x7 /JOB [job id] ...." for this purpose. Please search this message board for detailed "how-to" instructions. This issues has been discussed several times.

: We are facing the following issue. Sometimes a job just hangs ( does not exit
: after completion )
: which makes other jobs to wait in the queue , until we shutdown and restart
: the program itself.
: What can be done to prevent this from happening ?

It is not possible to single out a job which hangs.
Any job could hang at any time. How can RunAndWait help in this case ?
We had selected detached in the past , it didn't help.
The Asynchronous option - says that it will help other jobs in the sames Queue
run simultaneously , we have tried that too, why doesn't it work ?
We will try to create a separate queue for this job

: Set the job to run detached to physically separate it from the scheduler.

: If by itself this doesn't solve the problem create another helper job that
: will launch this one and then kill it after certain time in cases if it
: hangs. You can use RunAndWait "24x7 /JOB [job id] ...." for this
: purpose. Please search this message board for detailed "how-to"
: instructions. This issues has been discussed several times.

From your description I can guess that the job hungs while executing notification action, that's why nether async. or detached help. What do you do on the job completion?

: It is not possible to single out a job which hangs.
: Any job could hang at any time. How can RunAndWait help in this case ?
: We had selected detached in the past , it didn't help.
: The Asynchronous option - says that it will help other jobs in the sames
: Queue
: run simultaneously , we have tried that too, why doesn't it work ?
: We will try to create a separate queue for this job