Any information pertaining to the IBM 3284 or 3286 also pertains to the IEM 3287,
3288 dnd the 3289 printers, unless
otherwise noted. PREREQUISITE PUBLICATIONS Order No. COREQUISITE PUBLICATIONS Order No. GC20-l807 In addition, for EREP processing the
following OS/VS Library publications are
required:
and No: SUPPLEMENTARY PUBLICATIONS !]L1IQ Order No. GC33-4010 RELATED PUBLICATION Order No. GC20-18l6 CMS/DOS is part of the CMS system and is
not a separate system. The term CMS/DOS is
used in this publication as a concise way
of stating that the DOS simulation mode of CMS is currently active; that is, the CMS command SET DOS ON has been previously issued.
The phrase "CMS file system" refers to
disk files that are in CMS's 800-byte block
format; CMS's VSAM data sets are not
included.
iv IBH VM/370 System Logic and Problem Determination--Volume 2

OF • ix CONVERSATIONAL MONITOR (CMS) ••• 2-1 INTRODUCTION TO CMS •• The CMS Command Language
The File System. • • • • Program Development ••• INTERRUPT HANDLING IN CMS. • SVC Interruptions. • • . • Internal Linkage SVCs •••• Other SVCs. • • • • •• Input/Output Interruptions • Termina: Interruptions • • Reader/Punch/Printer Interruptions User-Controlled Device Interruptions • .2- 3
.2- 3
.2-4
.2- 5
.2-7
.2-7
.2-7
.2-7
.2- 8
.2- 9
.2- 9 • 2-9
.2-9 Program Interruptions •••• External Interruptions • • • • Machine Check Interruptions. • • • • 2- 10 . 2-10 FUNCTION AL INFORMAr ION • • 2- 11 Usage .. • • • 2-11 Structure of DMSNUC. • • 2-11 U:JERSSCT (User Area) •••••• 2-12 DEVT AB (Device rable) • • • 2-12
Structure of CMS Storage •• 2-12 Free Storage Management. • • • • 2- 14
GETMAIN Free Storage Management .•• 2-14 DMSFREE Free Storage Management. 2-17
Releasing Allocated Storage ••••• 2-21
DMSFREE Service Routines •••••• 2-22
Error Codes from DMSFRES, DMSFREE, and DMSFRET • • • • • • • • •• 2-24 CMS Handling of P SW Keys • • • . • • 2- 25 CMS SVC Handling •••••••••• 2-26 SiC Types and Linkage Conventions •• 2-26 Search Hierarchy for SVC 202 •••• 2-28 User and Transient Program Areas •• 2-29
Called Routine Start-Up Table •••• 2-31
Returning to the Calling Routine. 2-31 CMS Interface for Display Terminals •• 2-34 Os MACRO SIMULATION UNDER CMS ••••• 2-35 OS Data Management Simulation ••••• 2-35
Handling Files that Reside on CMS Disks • • • • • • • • • • 2-35
Handling Files that Reside on OS or DOS Disks • • • • • • • . 2-36
Simulation Notes • • • • • • • 2-38
Access Method Support. • • 2-42
Reading OS Data Sets and DOS Files Using Os Macros • • 2-45 DOS/VS SUPPORT ONDER CMS ••••••• 2-48 CMS Support for OS and DOS VSAM Functions • • • • • • • • • 2-48 CMS METHOD OF OPERATION AND PROGRAM ORGANIZATION. • ••••••••••• 2-51 Contents INITIALIZATION OF THE VIRTUAL MACHINE ENVIRONMENT . • • • • •• 2-57
Initialization: Loading a CMS Virtual Machine from Ca ra. Reader. • • • 2- 57
Initializes Storage Contents and System Tables • • • • • • • • 2-58
Processes IPL Command Line
Parameters. • • • • • • • • • 2-58
Initialize OS SVC-Handling without
the Use of the CMSSEG Segment ••• 2-59
Initializing a Named or Saved System • 2-bO Handling the First Commanj Line Passed to :MS. • • • • • • • • • • • • • • • 2-60 Setting and QueryinJ Virtual Machine Environment Options ••••••••• 2-60 DMSSET: SET DOS ON (VSAM) Processing 2-60 DMSSET: SET SYSNAME Processing ••• 2-61 PRCCSSSING AND EXECUTING CMS PILES •• 2-62 an Interactive Console
Environment e • • • • • • • • 2-62 Console Management and Command
Handling in CMS • • • • • 2-62
Maintaining an Interactive
Command/Response Session ••••••• 2-62
Execute Commands Passed via DMSINS • 2-63
Handle Commands Entered During a CMS Terminal Session •••••••••• 2-63 Method of Operation for DMSINT • • • • 2-64
Method of Operation for DMSITS •••• 2-65
Types of SVCs and Conventions • • • • • • • • • • • • 2-66
Search Hierarchy for SVC 202 • • • • 2-68 User ana Transient Areas • • 2-68
Called ROlltine Start-Up Tabl e.. 2-69 Returning to the Caller ••.•••• 2-69 System ana User Save Area 2-70 Load and :sxecute Text Files. • • • • • 2-71 SL: :ard Routine • • • • • . • • • • 2-72
rcs Card Routine -C2AE1 .. •••• 2-73 ESD Type a Card Routine -C3AA3. 2-74 ESD Type 1 Card Routine - ENTESD • • 2-74 ESC Type 2 Card Routine - C3AH1. 2-75 ESD Type 4 Routine -pc. . . .• 2-76 ESD TYFes 5 and 6 Card Routine - PRVESD ana. COMESD ••••••••• 2-76 ESD Type 10 Routine - WEAK EXTRN • • 2-77 TXT :ard Routine -C4AA1 • • •• 2-77 REP C3.rd RO;Jt.ine - C4AA3 •••••• 2-78
END Card Routine -C6AA1 • • • 2-80 Control Card Routine -CTLCRD1 . 2-81 REFAD R Routine (DMSLDRB) • • • • 2- 82 PRSERCH Routine (DMSLDRD). • • • 2- 82
Loader Data Ba ses. • • • • • • 2- 83 ESIDTB Entry • • • • • •• • •• 2-83 Pa tch Control Block (PCB). • • • 2- 85
Loader Input Restrictions. • • 2-85 Processing Commands That Manipulate the File System. • • • • • • • 2-85 Managing the CMS File System ••••• 2-86
Contents v