The IOB is used the parameter block for an EXCP request. Here it is modeled after the MVS control block.
@IOB DSECT , IOBFLG1 DS X FLAG BYTE IOBFLG2 DS X FLAG BYTE IOBSENS0 DS X SENSE BYTE 0 IOBSENS1 DS X SENSE BYTE 1 IOBECBCC DS X COMPLETION CODE IOBECBPT DS AL3 ECB ADDRESS IOBFLG3 DS X FLAG BYTE IOBCSW DS XL7 CHANNEL STATUS WORD IOBSIOCC DS X SIO CONDITION CODE IOBSTART DS AL3 CCW ADDRESS IOBFLG4 DS X FLAG BYTE IOBFUCBP EQU X'80' DCB ADDRESS POINTS TO UCB * IOBDCBPT DS AL3 DCB ADDRESS IOBRESTR DS XL4 IOBINCAM DS XL2 IOBERRCT DS XL2 IOBSEEK DS XL8 SEEK ADDRESS IOBLEN EQU *-@IOB
The ECB address points to a ECB that will be posted when the EXCP request is complete. If the IOBFUCBP flag is set in IOBFLG4 then IOBDCBPT is the address of a UCB instead of the address of a DCB.
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