I agree with Mr Sample; this is not a security issue.
Mr. Sample's idea to use job class for this purpose is legitimate, but realize this is for steps, not for the job.
Many sites impose very restrictive time limits for the default job class.
Using the job class to impose a time limit can backfire, though. I have often been trapped by a small step limit even when the job time is more than adequate for what I was doing.
The step limit can be updated by a JES2 command, though the JES2 parameters would have to be updated and JES2 restarted to make the change "permanent." The comannd is $TJOBCLASSx,TIME=(0,seconds)