A method for operating a rack system preferably in a dispatch unit (1), with a rack (2) and an associated rack serving device for the storage and retrieval of containers (3), trays or the like to or from the rack. A rack region of the rack (2) has a plurality of rack planes (13) arranged one above the other and is served by a dedicated, mechanically coupled, height and length-adjustable rack serving device (4). In each track region embodied as an independent, closed rack unit (A, B, C), containers (3), trays or the like undergo interim storage in a buffer zone (P1, P2, P3) on the same level, are transferred for storage or retrieval and transported by an elevator (5; 6a, 6b) and/or a preferably horizontal transport connection (F1, F2) arranged in the region of the rack unit (A, B, C) at the same level, from or to a transport system or workplace outside the rack system.