Waiting for selection may mean:
- the job cannot run beause all initiators for the class are in use
- the job cannot run because it requires exclusive access to a dataset that is in use by another job
- the job class has no initiators assigned at that moment
among other reasons.
As enrico mentioned, only your site support group can help you with the actual reason and maybe get the job running. Furthermore, most SDSF commands are designed to work on executing jobs -- there's not much you can do to a job waiting to execute (except cancel it, of course).