The I\/O Request Block (IORB) defines an I\/O request. \u00a0The IORB may be for an active I\/O request being processed by the device, it may be a queued request waiting on a device or it may be a completed I\/O request.<\/p>\n
An IORB is scheduled to a device by the TXXSIO (Schedule I\/O) module. \u00a0The UCB has a pointer to a queue of IORB requests. \u00a0The top IORB on the UCB queue is the active request.<\/p>\n
@IORB DSECT , \r\nIORBNEXT DS A NEXT IORB ON CHAIN \r\nIORBUCB DS A UCB ADDRESS \r\nIORBIOB DS A IOB ADDRESS \r\nIORBCCW DS A CCW ADDRESS \r\nIORBTCB DS A TCB TO BEE DISPATCHED ON COMPLETION\r\nIORBDIE DS A DISABLED EXIT ROUTINE \r\nIORBPCI DS A PCI EXIT ROUTINE \r\nIORBERR DS A ERROR EXIT ROUTINE \r\n* \r\nIORBFLAG DS X FLAGS \r\nIORBFSEN EQU X'80' RESCHEDULE FOR SENSE \r\nIORBOFLN EQU X'01' SECHED I\/O TO OFFLINE DEVICE \r\n* \r\nIORBECBC DS X I\/O COMPLETION CODE \r\nIORBSEN0 DS X SENSE BYTE ZERO \r\nIORBSEN1 DS X SENSE BYTE ONE \r\nIORBCSW DS XL8 CSW \r\n* \r\nIORBWORK DS XL64 WORK AREA<\/pre>\nThe IORBNEXT field is used to maintain the IORB queue off the UCB. \u00a0They are queued oldest to newest. \u00a0IORBUCB points to the UCB the I\/O request is for. \u00a0The IORBIOB points to the IOB associated with the EXCP request that created the IORB. \u00a0The IORBCCW points to the CCW program.<\/p>\n
IORBTCB points to a TCB that will be added to the dispatch chain when the I\/O is complete. \u00a0The TCB is supplied by the caller of the TXXSIO routine. \u00a0The TCB PSW should point to a routine that will handle the completion of the I\/O request. \u00a0The TCBDIE field contains the address of a routine that will be called from the I\/O Interrupt routine.<\/p>\n
The status fields (IORBECBC, IORBSEN0, IORBSEN1, and IORBCSW) return the status of the completed I\/O request.<\/p>\n
The IORBWORK is a 64 byte work area to be used by TXXSIO.<\/p>\n
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The I\/O Request Block (IORB) defines an I\/O request. \u00a0The IORB may be for an active I\/O request being processed by the device, it may be a queued request waiting on a device or it may be a completed I\/O … Continue reading