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Initiating the Channel Program z/OS DFSMSdfp Advanced Services SC23-6861-01 |
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Issuing EXCP or EXCPVR macro requests execution of the channel
program specified in the IOB. The system validates the request by
checking fields of the control blocks associated with this request.
If the system detects invalid information in a control block, it initiates
abnormal termination procedures. The system gets the address of the:
If this is an EXCPVR request and you have provided a page-fix appendage, the system passes control to it to allow you to either page fix your channel program and data areas, or to provide EXCP with a page fix list so that EXCP will do the page fixing. For a description of the page-fix appendage and its linkage to the system, see Page Fix and EXCPVR Start I/O Appendage. If you have provided a start I/O (SIO) appendage, the system passes control to it. The system does not examine the channel program until the return from the SIO appendage.The return address from the SIO appendage determines whether the system executes or skips the I/O operation. For a description of the SIO appendage and its linkage to the system, see Start-I/O Appendage. |
Copyright IBM Corporation 1990, 2014
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