Datastage includes a scheduling option, it does not have its own. DataStage doesn't include a "scheduler" so leverages the underlying O/S. For UNIX that means cron and a check of the crontab entries for the scheduling user will have what you need. DataStage leverages cron for recurring schedules and at for 'one off' schedules. For Windows, it uses scheduled tasks of Windows.
From the operating system command line, logged in as the scheduling user, a "crontab -l" will list the scheduled jobs.