File No. S360-30 Form C28-6537-1 OS Systems Reference Library IBM System/360 Operating System Data Management This publication contains information concerning the data management facilities of the IBM System/360 Operating system. It provides programmers coding in the assem­ bler language with the information neces­ sary to deSign programs using these facili­ ties. This publication describes the catalog­ ing, space allocation, and data access features of the operating system. Informa­ tion is also included on record and label formats and data organizations. PREFACE This publication, primarily directed to glossary of IBM System/360 Operatinq Sys­ applications programmers coding in the tem: Concepts and Facilities, Form assembler language, is a guide to the data C28-6535. management facilities of the System/360 Operating System. Because it provides detailed information on the facilities It is suggested that the reader be available and how they are used, program­ familiar with the information contained in mers coding in a language other than the the prerequisite publications listed below, assembler language will also find this as well as with the functional and opera­ publication useful. tional characteristics of direct-access devices as described in the recommended ,This is one of a group of publications publication. that describe the organization, functions, and applications of the System/360 Operat­ ing System. Detailed information on and PREREQUISITE PUBLICATIONS coding specifications for the macro­ instructions and the control statements IBM System/360 Operating System: Intro­ described herein may be found in the duction, Form C28-6534 publications IBM System/360 Operating Sys­ tem: control Program Services, Form IBM System/360 Operating System: Con­ C28-6541 and IBM System/360 Operating Sys­ cepts and Facilities, Form C28-6535 tem: Job control Language, Form C28-6539, respectively. RECOMMENDED PUBLICATION Terms used in this publication are IBM 2841 Storage Control Unit, Form defined either in the text or in the A24-3254 MAJOR REVISION (April, 1966) This edition, Form C28-6537-1, obsoletes Form C28-6537-0. significant changes have been made throughout the manual, and this new edition should be reviewed in its entirety. This publication was prepared for production using an IBM computer to update the text and to control the page and line format. Page impressions for photo-offset printing were obtained from an IBM 1403 Printer using a special print chain. copies of this and other IBM publications can be obtained through IBN Branch Offices. A form for readers' comments appears at the back of this publication. It may be mailed directly to IBM. Address any additional comments concerning this publication to the IBM Corporation, Programming Systems Publications, Department D58, PO Box 390, Poughkeepsie, N. Y. 12602 ©by International Business Machines Corporation, 1965, 1966 CONTENTS INTRODUCTION • • 7 Space Allocation for Indexed Sequential Data Sets. 25 Data Set Control 7 Direct Organization • • • • • • • 26 Insertion of Blocks. • • • • • • • 26 Data Access. • • 7 Telecommunications Organization • • • 27 DATA SET CONTROL FACILITIES. 9 Data Set Definition. • • • • • • 27 Data Control Block. • 27 Data Sets ........... 9 Job File Control Block • • • 28 Data Set Names. 9 Data Set Label • • • • • • 28 DCB -- Define Data Control Block • 29 Data Set Cataloging ••• • • •• 9 DD Statement/DCB The Catalog • • • • 9 Macro-Instruction Relationship. • 30 Control Volumes. • ••• 9 Structure of Catalog Indexes • 10 DATA ACCESS METHODS. • • • 31 Volume Indexes • • • • • 10 Cataloging Data Sets. • • • • • • 10 Macro-Instruction Languages. • • • 31 Generation Data Groups. • • • • • 10 L~nguage for Queued Access. • • 31 Relative Generation Numbers. • • • 12 Language for Basic Access • • 31 Absolute Generation Names. • • 12 Data Event Control Block (DECB) •• 32 Cataloging Generation Data Groups • • 12 Classification of Access Methods. • 32 Data Set Security Protection • .. • 13 Execute Channel Program (EXCP) Accessing Procedure. .. • • • .• • 32 Data Set Storage and Volumes • • • • 13 OPEN and CLOSE Macro-Instructions • • 33 Data Storage on Direct-Access Use of OPEN and CLOSE. • 33 Volumes. • '. • '. • • • .. • • 13 Volume Initialization. • • • • 14 Buffers and Buffer Pools • • • 35 Storing a Data Set • • • • • • 14 Assembly Time Buffer Pool Direct-Access Volume Options • 15 Construction • •• • • • '. • • • • • 35 Data Storage on Magnetic Tape BUILD -- Bui ld a Buffer Pool • 35 Volumes. • • .. • • • • .• • 15 Object Time Buffer Pool Volume Labeling • • • • • • • 15 Construction • • • • • • • •• • 35 Magnetic Tape Labels • • • 16 GETPOOL -- Get a Buffer Pool • 35 Magnetic Tape Volume FREEPOOL -- Free a Buffer Pool • • 36 Organization. • • • • 17 Direct-Access Labels • • • 18 Access Methods for Sequential Data Sets. • • • • • 36 Data Set Record Formats. • 19 Data Format-Device Type Blocks •••••••••• • 20 Relationships. • • • • • 36 Logical Records • • 20 Card Readers and Punches • • 36 Record Blocking • • • 20 Printers • • • • • '. • • 36 Record Formats. • 20 Paper Tape Reader. '. • • • · 36 Fixed-Length (Format F) ... • • 20 Magnetic Tape. • • '. • • • 36 Variable-Length (Format V) • 21 Direct-Access Devices. • • • 36 Undefined (Format U) • • • 21 Chained Scheduling. • • • • • • 37 Control Character • • • • 21 Queued Sequential Access Method. • 37 Data Set Organizations • • • 22 Record Formats. • '. • • • • • • • 37 Sequential Organization • • 22 Buffering Considerations. • • •• 37 Space Allocation for Sequential Buffer Pool Construction • • 37 Data Sets • • • • • • • • 22 Buffer Assignment Procedures • 38 Partitioned Organization ••••••• 22 Buffering Techniques. • • 38 Directory. • • '. •• '. • • • • 23 Simple Buffering • • • • 38 Space Allocation for Partitioned Exchange Buffering • • 38 Data Sets • • • • • • • • • • • • 23 Macro-Instructions. • • • • 39 Indexed Sequential Organization • 23 GET -- Get a Logical Record. • 39 Indexes. • • • • • • • • • 24 RELSE -- Release an Input Buffer • 40 Master Index • • • • • • 24 PUT -- Put a Logical Record. • • • 40 Insertion of Records • • • 25 PUTX -- Put From Existing Data Overflow Area. • • • • • • 25 Set • • • • • • • .. • • • • • • • 40 TRUNC -- Truncate an Output Concatenation of Partitioned Data Buffer. • • • • • • • • • • • • • 41 Sets • • • • .• • • • • • • • • • 52 FEOV -- Force End of Volume. • • • 41 Basic Partitioned Access Method CNTRL -- Control a Printer or Compatibility_ • • • • • • • • • 52 Stacker • • • • • • • • • • 41 PRTOV -- Test for Printer Queued Indexed Sequential Access Overflow. • • • • • 42 Method. • • • • • • • • '. • • 53 Error Conditions. • • • • 42 Record Formats. • • • • • • 53 Input Operations • • • • • •• 42 Format F, Unblocked. • • 53 output Operations. • • • • •• 42 Format F, Blocked. • • • • • • 54 Error Conditions: Internal Details •• 42 Forma t V, Unbloc ked. • • 54 Input Operations • • • • • •• 42 Format V, Blocked. • • • • • • 54 Output Operations. • • • • •• 42 Overflow Records • • • • 55 Error Analysis Routine Delete Codes • • • _ • • 55 (Synchronous Error Exit). • • 42 Buffering Considerations. • 56 Programming Notes • • • • • • • 43 Buffer Pool Construction • 56 Direct-Access Volume Options • • • 43 Buffer Assignment Procedures • 56 Update-in-P lace. • • • • • • • • • 43 Macro-Instructions. • • • • • • • 56 Concatenated Data Sets • • • • • • 43 PUT -- Put a Logical Record. • 56 Read Backwa rds • • . • • • • • • • 44 GET -- Get a Logical Record.. 56 Blocking of Variable-Length RELSE -- Release an Input Buffer • 57 Records • • • • • • • • • •• 44 SETL -- Set Lower Limit of Scan. • 57 ESETL -- End of Scan • • • • • • • 57 Basic sequential Access Method • • 44 PUTX -- Return a Logical Record. • 57 Record Formats •••••••• • 44 Exceptional Conditions,. • • • • • • • 58 Buffering Considerations. • • • • 45 Creating An Indexed Sequential Data Buffer Pool Construction • • 45 Set. • • • • • • • • • • • • • • 59 Buffer Assignment Procedures • • • 45 Programming Notes ,. • • • • • • • 60 GETBUF -- Get a Buffer From a Direct-Access Volume Option. • 60 Pool. •• • • • • • • • 45 Blocking of Variable-Length FREEBUF -- Return a Buffer to a Records • • • • • • • • • • • 60 Pool. • • • • • • • • • • 45 Macro-Instructions •••• • • 45 Basic Indexed Sequential Access Method • 60 READ -- Read a Block • • • • • 45 Record Formats,. • • • • 60 WRITE -- Write a Block • 46 Buffering Considerations. • • • • 60 CHECK -- Wait for and Test Buffer Pool Construction • • • 60 Completion of Read or Write Buffer Assignment Procedures • 61 Operation • • • • • • • • • • • • 46 FREEDBUF -- Free a Dynamically FEOV -- Force End of Volume. • • • 47 Obtained Buffer • • • • • • • 61 CNTRL -- Control On-Line Macro-Instructions. • • • • • • • 61 Input/Output Devices. • • • 47 READ -- Retrieve a Logical PRTOV -- Test for Printer Record. • • • • • • • • • 61 Overflow. • • • • • • • • • • 47 WRITE -- Write a Logical Record. • 62 NOTE -- Provide Position Exceptional Conditions. • • • • • • • 62 Feedback. • • • • • • • • • • 47 Reorganizing an Indexed Sequential POINT -- Point to Block. • • • 47 Data Set • • • • • • • • • • 63 BSP -- Backspace One Block • • 48 Programming Notes ••• • • • • · 63 Error Conditions. • • • • • 48 Overflow Records • • • • • • • • • 63 Programming Notes • • • • • 48 Direct-Access Volume Option. · 63 Direct-Access Volume Options • • • 48 Update-in-Place. • • • • • • • • • 48 Basic Direct Access Method • • 63 Read Backwards and Concatenated Record Formats,. •• • • • • 64 Data Sets .