The batch schedule and the critical path
Thousands of jobs run every night in a dependency order held by a scheduler. The schedule, not the JCL, is the real map of the overnight — and one chain through it determines whether everything finishes on time.
What the scheduler holds
- Jobs and their dependencies — which must finish before which can start.
- Calendars — working days, month ends, quarter ends, holidays. Month end is a different schedule.
- Resources — limits so that, for example, only three heavy jobs run at once.
- Triggers — a file arriving, a time being reached, an external system signalling.
- Actions on failure — alert, hold successors, auto-restart, or run a recovery job.
Common schedulers and shared vocabulary
Sites use Control-M, CA-7, IWS/TWS, Zeke or similar. The products differ; the concepts do not.
| Term | Means |
|---|---|
| Job stream / application | A group of related jobs run together |
| Predecessor / successor | What must run before / what runs after |
| Hold / release | Stop a job being submitted / let it go |
| Force complete | Mark a job as done without running it — powerful and dangerous |
| Rerun / restart | Run again from the top / resume from a step |
| SLA | The time by which a stream must complete |
Reading the night ahead
- Check the schedule is running to time against its usual profile.
- Identify anything already late and whether it is on the critical path.
- Check for held jobs left over from a previous shift.
- Note anything unusual on tonight's calendar — a month end, a one-off run, a deployment.
Doing this at the start of a shift takes ten minutes and prevents most of the surprises that come from inheriting a situation you did not know about.
Common mistakes
Successors may already have run against partial output, so restarting alone does not fix the data.
Month end, quarter end and holidays run different streams. Check the calendar.
It hides the failure and lets downstream jobs consume bad or missing data.
What you will see at work
- Learn to read your scheduler's monitor screen fluently. It is the single most-used tool in the role.
- Ask for the critical path diagram for your applications. If none exists, drawing one is high-value work.
- Manual interventions should be logged even when they succeed, so the next shift understands what state the night is in.
Key terms
Check your understanding.
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