900-CREATE-JOB updating current job gives error

Getting WSJR-ERROR = Y when updating the currently running job using 900-CREATE-JOB (works fine if I use a different JOBREQ-JOB-NAME) 

I suppose this makes sense, since in lapm you can't update a job if its in queue (e.g. in recovery)

What I'm trying to do is run a job but override some parameters using logic with db lookups.  Has anyone accomplished this?  If not cobol I also tried design studio but there's no straightforward way there to update the job definition either.

I can override the in-memory PRM-* values fine, but what I can't figure out how to do is how to update the job definition itself