A method, apparatus, and computer program product for processing a chained-pair linked transport control channel program in an I/O processing system is provided. The method includes receiving a first command message at a control unit specifying that a device command word (DCW) list is encoded in a data message associated with the first command message as part of the chained-pair linked transport control channel program. The method further includes receiving a second command message chained-pair linked to the first command message, the second command message specifying data attributes associated with the DCW list. The method additionally includes extracting the DCW list from the data message in response to receiving the data message, and executing the DCW list.