Patent ID: 8117347
Filing Date: 2012-02-14
Classification: G06F

Abstract:
1. A computer program product for facilitating input/output (I/O) processing for an I/O operation at a host computer system configured for communication with a control unit, the computer program product comprising: a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising: obtaining a transport command word (TCW) for an I/O operation, the TCW comprising a flag field comprising a flag, and a transport command control block (TCCB) address field comprising a TCCB address, the flag indicating whether the TCCB address field directly or indirectly addresses a TCCB; obtaining a TCCB from a location identified by the TCCB address responsive to the flag having a first value indicating direct addressing, the TCCB comprising a header and a variable length transport control area, the header comprising information about the variable length transport control area, the variable length transport control area comprising one or more I/O commands; gathering the TCCB from one or more locations specified by a list of addresses identified by the TCCB address responsive to the flag having a second value indicating indirect addressing, the TCCB comprising a header and a variable length transport control area, the header comprising information about the variable length transport control area, the variable length transport control area comprising one or more I/O commands; and forwarding the TCCB to the control unit for execution.