As long as parameter value job_queue_processes > 0, the job will execute...
You shut the database down... If the job is running, it is treated like any other
user on the database ... shutdown immediate will wait for the current trx to complete before taking the db down... Upon reboot, the job is still in the queue to be run at it's next scheduled run time ... If you don't want it to run,
you can "BREAK" the job (broken status) or alter system set job_queue_processes=0;