By setting the value of 0 to the parameter “job_queue_processes” one can suspend all jobs from executing in DBA_JOBS. The value of this parameter can be changed without instance restart.

-- see current value of the parameter
SQL> show parameter job_queue_processes;

NAME TYPE VALUE
———————————— ———– ———–
job_queue_processes integer 1000

-- Set the value of the parameter in memory, which will suspend jobs from starting
SQL> alter system set job_queue_processes=0 scope=memory;

System altered.