What you mean by hung? it goes to queue?
How do you get the workflows? Is there a call from serviceNow to Process Automation or you just do a Webservice/DB query and get the incidents you have to close?
If this is the case, you have, as you can imagine, several options.
In most options, you should use Resources (Resources - CA Process Automation - 4.3 - CA Technologies Documentation )
What I would do is:
If serviceNow Call pam directly to close de incident, it would be something like that:
If you have to get the incidents and close all that match the criteria, it would look like this
And That would work because you would run the CloseIncidentProcess as detached Mode
So it would start executing all the processes in parallel until the resource lock is met (you have to read about this on the link at the beginning).
You should define how much parallel execution could be done and that wouldn't "hung" your application and make that the amount of the defined Resource:
Inside the close Incident, you should, at the end of the process (both if it fails or if it succeeds) to release a resource
On Main editor
In the exception lane something like this
Or if you have both on main editor, just do something like this