Practical Usage of TSO REXX

Transcription

1 Practical Usage of TSO REXX

2 Springer London Berlin Heidelberg New York Barcelona Hong Kong Milan Paris Singapore Tokyo

3 Anthony S. Rudd Practical Usage of TSOREXX 3rd revised edition t Springer

4 Anthony S. Rudd, BSc, MSc (Hons) ISBN-13: DOl: / e-isbn-13: British Library Cataloguing in Publication Data Rudd, Anthony S. Practical usage oftso REXX. - 3rd ed. 1. REXX (Computer program language) I. Title II. Practical usage ofmvs REXX 005.2'62 ISBN Library of Congress Cataloging-in-Publication Data Rudd, Anthony S., Practical usage oftso REXX I Anthony S. Rudd rd ed. p.cm. 1. REXX (Computer program language) 2. Time-sharing computer systems L Title QA R24 R '28-dc Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted. in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency. Enquiries concerning reproduction outside those terms should be sent to the publishers. Springer-Verlag London Limited 2000 Softcover reprint of the hardcover 3rd edition 2000 The use of registered names, trademarks etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant laws and reguiations and therefore free for general use. The publisher makes no representation, express or implied. with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made. Typesetting: Camera ready by author 34/ Printed on acid-free paper SPIN

5 Preface The aim of PRACI'ICAL USAGE OF TSO REXX is to show the practical use of REXX in the OS/390 TSO/E environment. The book covers not only the basic language elements but particularly emphasises the expansibility of REXX. In addition to its use as a procedures language, one of the major uses of REXX is interfacing to and from other components. Consequently, the major part of this book is devoted to the interfacing aspects of REXX. The chapter on the programming interfaces includes a wide range of examples in Assembler, C (C+ +), COBOL, and PLlI. This third edition of the book, previously titled PRACI'ICAL USAGE OF MVS REXX, has been revised to discuss the new REXX features introduced for the OS/390 TSO/E environment. It also includes two new chapters that cover the REXX compiler and provide a general discussion of the implementation aspects of using REXX as a programming language. For historical reasons, the TSO/E REXX implementation uses the term MVS as synonym for the host operating system environment (e.g. OS/390 in this case). At this point I would like to thank Detlef Insel for his help.

6 Table of Contents Preface... v 1. Introduction 1.1 REXX background REXX characteristics REXX applications REXX'S future REXX Facilities Introduction... 4 REXX structure... 8 Token... 8 Literal string... 8 Hexadecimal literal string... 9 Binary literal string Symbol Numeric symbol Variables Operator Prefix operators Arithmetic operators Abuttal operator Comparative operators Logical operators Implicit concatenation operators Other syntax elements... 17

7 viii TABLE OF CONTENTS 2.3 REXX expressions Arithmetic expression Comparative expression Logical (Boolean) expression Statements Invocation of a REXX exec Comparison with CLISTS REXX Processing Elements Introduction Statements Routines..., Subroutine Procedure Function Search order Invocation Parameters (arguments) Return Communication between execs Types of instruction... '" Conditional control Loop control Control processing flow Assignment Stack (queue) processing Stack as terminal input buffer Stack used for general data storage Stack used for passing data between execs File buffer..., Parsing Debugging Miscellaneous instructions Commands Special variables RC - Return code RESUL T - Function result SIGL - Source line number REXX Instructions 4.1 Introduction Instruction descriptions ADDRESS - Set environment ARG - Fetch argument CALL - Invoke routine DO - Define start of Do-block DROP - Free variable EXIT - Terminate exec IF - Conditional execution INTERPRET - Interpret statement... 59

8 T ABLE OF CONTENTS ix ITERATE - Terminate the current cycle in the Do-loop LEAVE - Terminate Do-loop NOP - No-operation NUMERIC - Define numeric formats OPTIONS - Pass special parameters to the language processor PARSE - Assign data PROCEDURE - Define internal procedure PULL - Fetch data element from the head of the stack PUSH - Set data element at the head ofthe stack QUEUE - Set data element at the tail of the stack RETURN - Return from routine SAY - Display SELECT - Select one condition from a series of conditions SIGNAL - Enable (or disable) an exception condition, or cause control to be passed to a routine (or label) TRACE - Set debugging options UPPER - Transform lowercase characters into uppercase = - Assign Command Examples Exception Handling 5.1 Introduction Condition traps ERROR condition FAILURE condition HALT condition NOVALUE condition SYNTAX condition Stacked conditions Explicit invocation String Processing 6.1 Introduction Word parsing Delimiter parsing Positional parsing Dynamic parsing Argument parsing Worked examples Numbers and Arithmetic 7. 1 Introduction Number Arithmetic operators Power (exponentiation) Multiplication Division Modulo (integer) division Remainder division... 99

9 x TABLE OF CONTENTS Numeric comparison... '" Precision and representation Computational base Retention of significance Arithmetic exceptions Sequence of operations Numeric formatting Input/Output 8.1 Introduction Data buffering Opening and closing the data files Terminal operations File-mode operations File positioning Write operation Delete data operation Read operation Update operation Debugging 9.1 Introduction Exception conditions Tracing options... III ALL - Display all expressions before execution COMMANDS - Display all commands before execution ERROR - Display all commands which return an error condition FAILURE - Display all commands which return a negative error condition INTERMEDIATE - Display all expressions (with intermediate results) before being executed LABELS - Display all labels as they are reached RESUL TS - Display all expressions (with end results) before being executed SYNTAX - Check syntax without processing the statements n - Suppress trace intervention Trace output Trace data prefixes Trace intermediate data prefixes Trace output example Interactive debug Interactive debugging example Parametric debug Errors with host commands and functions REXX Built-in Functions 10.1 Introduction Function-like (direct) invocation Call invocation

10 TABLE OF CONTENTS xi Internal functions Function side-effects Invocation errors Internal data format Function definitions ABBREV - Test whether string is an abbreviation ABS - Return absolute value ADDRESS - Return name of current environment ARG - Return argument BITAND - Logical And B ITOR - Logical Or BITXOR - Logical Exclusive-Or B2X - Convert binary data to hexadecimal CENTRE (CENTER) - Centralise data COMPARE - Compare CONDITION - Return condition COPIES - Replicate data C2D - Convert character data to decimal C2X - Convert character data to hexadecimal DATA TYPE - Determine data type DATE - Return current date DELSTR - Delete substring DELWORD - Delete words DIGITS - Return the NUMERIC DIGITS setting D2C - Convert decimal to character D2X - Convert decimal to hexadecimal ERRORTEXT - Return message text FIND - Search for word FORM - Determine NUMER I C FORM setting FORMAT - Format numeric value FUZZ - Determine NUMERIC FUZZ setting INDEX - Search for substring INSERT - Insert substring JUST! FY - Justify string of words LASTPOS - Determine last position of phrase LEFT - Left-align string LENGTH - Determine length of string LINESIZE - Return the (maximum) width of a terminal line MAX - Determine the maximum of a series of numeric values MIN - Determine the minimum of a series of numeric values OVERLAY - Overlay part of a string with a phrase POS - Search for substring QUEUED - Determine the number of entries in the queue RANDOM - Generate a (pseudo-)random number REVERSE - Reverse the sequence of data RIGHT - Right-align string SIGN - Determine numeric sign SOURCELINE - Return "program line"

11 xii TABLE OF CONTENTS SPACE - Insert fill-character between words STRIP - Remove padding-characters at the start or end of a string SUBSTR - Extract substring SUBWORD - Extract series of words from word-string SYMBOL - Determine the status of a symbol TIME - Return the current time-of-day TRACE - Return (and set) current trace mode TRANSLATE - Translate characters TRUNC - Truncate numeric value USERID - Return Userid VALUE - Return (and set) the contents of a symbol VERI FY - Test whether only characters in a phrase are present in string WORD - Fetch word WORD INDEX - Determine the character position of a word in a string of words WORDLENGTH - Determine word length WORDPOS - Determine the word-number of word in a word-string WORDS - Determine the number of words in a word-string XRANGE - Define a range of hexadecimal values X2B - Convert hexadecimal to binary X2C - Convert hexadecimal to character X2D - Convert hexadecimal to decimal Examples... " Host REXX Commands 11.1 Introduction Host REXX command definitions DELSTACK - Delete stack DROPBUF - Release buffer EXECIO - Perform input/output operation EXECUTI L - Specify execution environment for REXX exec HE - Halt execution HI - Halt interpretation HT - Halt typing MAKEBUF - Create new buffer in the stack NEWSTACK - Create a new stack QBUF - Query buffer QELEM - Query elements QSTACK - Query stack RT - Resume typing SUBCOM - Confirm the host environment TE - Trace end TS - Trace start Example MVS Command Functions 12.1 Introduction

12 TABLE OF CONTENTS xiii MVS command function calls GETMSG - Retrieve a console session message L1STDSI - List (obtain) dataset information MSG - Set (interrogate) CLIST CONTROL MSG option MVSVAR - Obtain information on MVS, TSO, and the current session OUTTRAP - Trap TSO display output PROMPT - Set (interrogate) CLIST CONTROL PROMPT option SET LANG - Set (interrogate) current language STORAGE - Set (interrogate) main-storage contents SYSCPUS - Obtain CPU information SYSDSN - Request dataset status SYSVAR - Fetch TSO system variable Invocation of other TSO commands Example REXX Invocation Introduction Invocation from TSO/ISPF Invocation from batch TSO Invocation from batch Linkage to the host environment Linkage to programs LINK (ATTACH) L1NKMVS (ATTACHMVS) L1NKPGM (ATTACHPGM) Interface with I SPEXEC (ISPF Dialog Manager) Interface with ISREDIT (ISPF/PDF Edit macro) Macro example Interface with DB2 (Database2) DB2 invocation example Interface with QMF (Query Management Facility) DSQCIX - QMF Callable Interface DSQCCI - QMF Command Interface Interface from programs with REXX System Interfaces Introduction General conditions C, C+ + restrictions Other program language restrictions Invocation of a REXX exec Interface from programs to batch REXX (IRXJCL) Invocation of a REXX exec using the TSO Service Facility (IJKEFTSR) Interface from programs to REXX processor (IRXEXEC) Sample program Invocation of an in-store exec Program access to REXX variables (IRXEXCOM service) Sample programs

13 xiv TABLE OF CONTENTS Sample retrieval program Stack processing (IRXSTK service) Sample programs Command interface Entry conditions Parameter list Exit conditions Examples Command registration interface (I RXSUBCM) Command router Function interface Entry conditions..., 248 Exit conditions..., 248 Sample function program Function package Function directory Load routine (IRXLOAD service) Initialisation routine (IRXINIT service) Sample initialisation program Get result (IRXRLT service) Sample I RXRL T program Control blocks Argument List EFPL (External Function Parameter List) ENVBLOCK (Environment Block) EV ALBLOCK (Evaluation Block) EXECBLK (Exec Block) INSTBLK (In-storage Control Block) SHVBLOCK (Shared Variable (Request) Block) VEEP (Vector of External Entry Points)... '" 268 Examples...,...,..., Assembler implementation C implementation COBOL implementation PLII implementation Worked Examples 15.1 Introduction Worked example Worked example Worked example Worked example Worked example REXX Compiler 16.1 Introduction JCL procedures REXXC procedure REXXCL procedure REXXCLG procedure

14 T ABLE OF CONTENTS xv REXXL procedure Compiler options Combining compiled objects Produce a statically loaded program Stubs CALLCMD stub CPPL stub EFPL stub CPPLEFPL stub MVS stub Performance Compatibilty Execution sequence Other Environments 17.1 Introduction REXX for CICS REXX for UNIX Services Program Development Introduction Reusability Productivity Standardisation Readability Reliability Maintainability Compatibility Performance Expansibility Stepwise refinement Portability Testing Run-time debugging Development with the REXX compiler Appendix A. Syntax Notation Appendix B. Glossary Index