z/VM Version 7 Release 1 CMS Application Development Guide for Assembler IBM SC24-6257-00 Note: Before you use this information and the product it supports, read the information in “Notices” on page 503. This edition applies to version 7, release 1, modification 0 of IBM® z/VM® (product number 5741-A09) and to all subsequent releases and modifications until otherwise indicated in new editions. Last updated: 2018-09-12 © Copyright International Business Machines Corporation 1990, 2018. US Government Users Restricted Rights – Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. Contents List of Figures..................................................................................................... xiii List of Tables........................................................................................................xv About This Document......................................................................................... xvii Intended Audience................................................................................................................................... xvii Where to Find More Information..............................................................................................................xvii Links to Other Documents and Websites........................................................................................... xvii How to Send Your Comments to IBM....................................................................xix Summary of Changes for z/VM CMS Application Development Guide for Assembler....................................................................................................... xx SC24-6257-00, z/VM Version 7 Release 1................................................................................................xx SC24-6163-02, z/VM Version 6 Release 4................................................................................................xx Part 1. Introduction.............................................................................................. 1 Chapter 1. The CMS Programming Interface.............................................................................................. 3 Overview of the CMS Programming Interface....................................................................................... 3 CMS Virtual Machine Environments................................................................................................. 3 CMS Programming Interface Groups..................................................................................................... 4 CMS Preferred Interface.........................................................................................................................5 CMS Preferred Macros...................................................................................................................... 5 CMS Preferred Routines....................................................................................................................9 CMS Preferred Functions.................................................................................................................. 9 CMS Compatibility Interface................................................................................................................ 10 CMS Compatibility Macros and Suggested Replacements............................................................ 10 CMS Compatibility Functions and Suggested Replacements........................................................11 Simulated OS/MVS Macros.............................................................................................................11 Chapter 2. CMS Operating Characteristics................................................................................................15 Overview of CMS Operating Characteristics........................................................................................15 CMS Command Search Order...............................................................................................................15 CMS Runs in Supervisor State..............................................................................................................16 How CMS Command Processing Works...............................................................................................16 Explicitly Releasing Resources.......................................................................................................16 The CMS Command Loop................................................................................................................17 SVC Levels.......................................................................................................................................17 Abend Processing........................................................................................................................... 18 Determining When CMS Reclaims Resources..................................................................................... 18 Saving Resources across Boundaries.................................................................................................. 20 Using Macro Libraries...........................................................................................................................21 Coding CMS Macros........................................................................................................................ 21 How CMS Macros Work...................................................................................................................22 CMS Macro Formats........................................................................................................................22 Chapter 3. Architecture............................................................................................................................. 23 ESA/XC, ESA/XA, 370-XA, and System/370 Architecture.................................................................. 23 ESA/XC, 370-XA, and System/370 PSWs............................................................................................23 31-Bit Addressing................................................................................................................................ 24 Conventions for 31-Bit Programs...................................................................................................24 Bimodal Addressing........................................................................................................................25 iii I/O Considerations..........................................................................................................................28 CMS Preferred Interface I/O Support.............................................................................................28 Using Diagnose Codes for I/O.........................................................................................................29 I/O Instructions.............................................................................................................................. 29 Assembler Instructions That Work Differently....................................................................................30 Instructions That Are Sensitive to Addressing Mode.................................................................... 31 Part 2. Using CMS Services..................................................................................33 Chapter 4. Program Invocation - Direct Branch Linkage.......................................................................... 35 Overview of Direct Branch Linkage...................................................................................................... 35 Using BAL/BALR with AMODE ANY Programs..................................................................................... 35 Switching the Addressing Mode...........................................................................................................35 AMODESW Formats........................................................................................................................ 36 Using AMODESW - Examples......................................................................................................... 36 Chapter 5. Program Invocation - Supervisor Assisted Linkage................................................................ 39 Overview of CMS Supervisor Assisted Linkage....................................................................................39 Supervisor Assisted Linkage — An Overview.......................................................................................39 Setting Up a Parameter List................................................................................................................. 41 Using the SCAN Macro.................................................................................................................... 41 Making the Call................................................................................................................................43 Call Charts.......................................................................................................................................45 Receiving Control..................................................................................................................................46 Register Usage................................................................................................................................ 46 USERSAVE