IBM GY28-6609-6 OPEN CLOSE EOV Program Logic Rel 21 Mar72 free download

File name GY28-6609-6_OPEN_CLOSE_EOV_Program_Logic_Rel_21_Mar72.pdf

File Number S360-30 Order Number GY28-6609-6 Program Logic OS OPEN/CLOSE/EOV Logic Release 21 Program Number 360S-DM-50B This publication, intended for system programmers and people who want to understand the Open/Close/End-of-Volume (EOY) portion of the operating system, describes the units of processing (functions) and units of code (modules) of Open/Close/EOV. Open opens a data set by linking system control blocks so that the access methods can perform the input/output operations requested by the user. EOV applies these linkages when the end of a volume of a multivolume data set is reached and performs end-of-data processing. Close closes a data set by restoring the system control blocks to the contents they had before the data set was opened. The book is divided into the following sections: Introduction, Method of Operation, Program Organization, Directory, Data Areas, and Diagnostic Aids. The latter section discusses how to use a set of routines called Problem Determination to find the causes of errors that occur during Open/Close/EOV processing. The reader is expected to be familiar with OS data management, as described in OS Data Management Services Guide, GC26-3746. Seventh Edition (March 1972) This is a major revision of, and makes obsolete, GY28-6609-5. The manual has been completely rewritten to correspond to the redesign of Open/Close/End-of-Volume. This edition applies to Release 21 of the operating system and to all subsequent releases unless otherwise indicated by new editions or technical newsletters. Changes to the information in this book may be made at any time, so before using this publication in connection with the operation of IBM systems, consult the latest SRL Newsletter, GN20-0360, for the editions that are applicable and current. Requests for copies of IBM publications should be made to your IBM representative or to the IBM branch office serving your locality. Forms for readers comments are provided at the back of this publication. If the forms have been removed, comments may be addressed to IBM Corporation, Programming Publications, Department D78, Monterey and Cottle Roads, San Jose, California 95114. @ Copyright International Business Machines Corporation 1968, 1969, 1970, 1971, 1972 PREFACE This publication describes the functions (units of processing) and modules (units of code) of the Open/Close/End-of-Volume portion of the operating system. It also describes the relationship of Open/Close/EOV to the portions of the operating system that give control to and receive con- trol from it. Open/Close/EOV modifies system control blocks, and mounts and verifies volumes so that I/O operations can be performed. This publication is divided into seven sections: "Section