SQL> SELECT NAME, value FROM v$parameter WHERE NAME LIKE '%job%';

NAME                     VALUE
---------                ---------
job_queue_processes      10

SQL> DECLARE
  2  v_id NUMBER;
  3  v_job_what VARCHAR2(400);
  4  BEGIN
  5      v_job_what := 'begin dbms_output.put_line (''YO''); end;';
  6      Dbms_Job.submit(job => v_id, what => v_job_what, next_date => SYSDATE,
INTERVAL => NULL);
  7  END;
  8  /

PL/SQL procedure successfully completed.

SQL> commit;

Commit complete.

SQL> SELECT job, what FROM dba_jobs WHERE last_date IS NULL;

       JOB   WHAT
----------   ---------------------------
      2355   begin dbms_output.put_line ('YO'); end;

SQL> exec dbms_job.run(2355);

PL/SQL procedure successfully completed.

SQL> SELECT job, what FROM dba_jobs WHERE last_date IS NULL;

no rows selected

SQL>

BEGIN
  FOR i IN 1 .. 120 LOOP
     Dbms_Lock.sleep(60);
     BEGIN
         FOR l_jobs IN (SELECT * FROM dba_jobs WHERE last_date IS NULL)
         LOOP
         dbms_job.run(l_jobs.job);
         END LOOP;
     END;
  END LOOP;
END;
/