Within both a stocker apparatus and a method for operating the stocker apparatus there is employed, in addition to: (1) a minimum of one input/output port; (2) an array of storage locations for storing an array of work in process (WIP) product units; and (3) a random access transportation means for transporting a work in process (WIP) product unit at least bidirectionally between the minimum of one input/output port and a storage location within the array of storage locations; (4) a controller for controlling the random access transportation means. Within the stocker apparatus and the method, the controller is programmed such that upon unavailability of the minimum of one input/output port and upon concurrent receipt of a request to retrieve a work in process (WIP) product unit stored within the array of storage locations to reposition the requested work in process (WIP) product unit to a designated storage location within the array of storage locations where it may be manually retrieved.