Input/Output Configuration Program: Difference between revisions

Revision as of 03:44, 11 May 2023

Revision as of 12:02, 28 May 2023

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| id = SA22-7085-1

| version = Second Edition

| date = January 1987}}</ref> mode, IBM changed the I/O architecture to allow the [[Channel Subsystem]] to handle the channel scheduling that the operating system had to handle in S/370 mode. The new I/O architecture used a 16-bit '''subchannel number''', a 16-bit device number and an 8-bit '''Channel Path IdIdentifier''' ('''Channel Path Id''' or '''CHPID'''); the [[Channel Subsystem]] was responsible for mapping the '''CHPIDsubchannel number''' to the channel and device numbers, for queuing I/O requests and for selecting from the available paths. Starting with [[System z9]], IBM offered the multiple-subchannel set facility, which allowed multiple independent sets of chaanel paths, each with its own 256 '''CHPID'''s.

The installation was responsible for defining the [[Input/Output Configuration Data Set]]s ('''IOCDS''''s), and the operator could select a specific '''IOCDS''' as part of a [[power on reset]] (POR). Input/Output Configuration Program (IOCP)<ref name=GC38-0097/><ref name=GC38-0401/><ref name=GC38-0456/> is a program for IBM mainframes that compiles a description of the [[Channel Subsystem]] and [[LPAR]]<ref name=GA22-7123/> configuration, optionally loading it into an [[Input/Output Configuration Data Set]] (IOCDS); it recognizes the syntax of [[MVS Configuration Program]] (MVSCP)<ref name=GC28-1615/> input, and there is no need to maintain separate input files.

The direct use of IOCP and [[MVS Configuration Program|MVSCP]] has been mostly supplanted by [[Hardware Configuration Definition| Hardware Configuration Definition (HCD)]].<ref name=GA22-7525/>