IBSYS itself was really a basic monitor program, that read control card images placed between the decks of program and data cards of individual jobs. An IBSYS control card began with a "$" in column 1, immediately followed by a Control Name that selected the various IBSYS utility programs needed to set up and run the job. These card deck images were read from magnetic tapes, prepared offline, not usually directly from the punched card reader.
Noble, A. S., Jr., "Design of an integrated programming and operating system", IBM Systems Journal, June 1963. "The present paper considers the underlying design concepts of IBSYS/IBJOB, an integrated programming and operating system. The historical background and over-all structure of the system are discussed. Flow of jobs through the IBJOB processor, as controlled by the monitor, is also described."