April 1, 1981 Or, Y01 can fetch a phase and begin executing it on a single line:
fetch proq2 (start
When VOl use the FETCH command without the START option, issues a
message tellinq you at what virtual storage address the phase is loaded: PHASE PROG2 ENTRY POINT AT LOCATION 020000 Location X'20000' is the starting address of the user program area for CMS; relocatable phases are always loaded starting at this address
unless vou soecify a different address using the ORIGIN option of the fetch proq3 (oriqin 22000 start
The executes beginning at location 22000 in the user
proqram area. SEARCH FOF EXECUTABLE PHASES When YOl execute the FETCH command, CMS searches for the phase name you
specify in the following places:
1. In a private core imaqe library on a DOS disk. If you have a private library you want searched for phases, you must identify
it usinq the ASSGN and DLBL commands, using the logical unit SYSCLB: 2.
assqn sysclb d
dlbl ijsyscl d dsn ? (sysclb
In eMS DOStIBs on eMS you must use eMS/DOS: disks. If you want
the GLOBAL command
qlobal doslib templib mylib DOSLIBs searched to identify them YOl can specify up to eight DOSLIBs on the GLOBAL command line.
for
to
3. On the DOS system residence core image library. If you want the system core image library searched you must have entered the CMS/DOS environment specifying the mode letter of the system
residence:
set dos on z
When yoa want to fetch a core image phase that has copies in both the
core imiqe library and a DOSLIB, and you want to fetch the copy from the eMS DOStIB, vou can bypass the core image library by entering the
command:
assqn sysclb ua
When Y01 need to use the core image library, enter:
assqn sysclb c where C is the mode letter of the system residence volume. You do not
need to reissue the DLBL command to identify the library. 176 IBM VM/370 CMS User's Guide

of GC20-1819-2 Rev 8arch 30, 1919 by SUppa SD23-9024-1 for 5148-XX8 8AKIBG I/O DEVICE ASSIGN8EBTS . If you are executing a program that performs I/C, you can use the ASSGN co •• and to relate a system or programmer logical unit to a real I/O device. As in DOS/VSE, device type assignment in CMS/DOS is dependent
on device specifications in the assgn syslst printer
assgn sys052 reader
In this example, your program is going to read input data from your
virtual card reader; the output print file is directed to your virtual
printer. If you want to reassign these units to different devices, you
must be sure that the files have been defined as device independent.
If you assign a logical unit to a disk, you should identify the file by using the DLBL command. On the DLBL command, you must always relate
the DLBL to the system or programmer logical unit previously specified
in an ASSGN command:
assgn sys015 b
dlbl myfile b dsn ? (sys015 When you enter the DLBL command with the? operand you are prompted to
enter the DOS file-ide You must issue all of the ASSGN and DLBL commands necessary for your
program's I/O before you issue the FETCH command to load the program
phase and begin executing. SPECIFYING A VIRTUAL PARTITION SIZE For most of the programs that you execute in C8S, you do not need to
specify how large a partition you want those programs to execute in. When you issue the START command or use the START option on the FETCH command, eMS calculates how much storage is available in your virtual
machine and sets a partition size. eMS calculates how much storage is
available in the following manner: FREELOWE - (MAINHIGH + (4096 * FRERESPG» where: FREELOiE equals the low extent of allocated sterage obtained from the
top of virtual storage downwards via the D8SFREE system
request. 8AINHIGH equals the high extent of allocated storage obtained from the
low virtual storage upwards via the GETMAIN user request fer
storage. FRERESPG equals the amount of storage to be reserved for subsequent
system requests, in pages.
In some instances, you may want to control the partition size: • For performance considerations • Because the default may not leave enough free storage to satisfy the
GET VIS commands issued by the DOS program or the access methcd
services function being executed. Section 9. Developing DOS Programs Under eMS 111