Generation Procedures Under VM/370 VM/370 can help considerably throughout the system generation process.
Probably VM/370's biggest advantage is the ability to generate the
system under VM/370 without disturbing the normal production activity.
The system programmer (or whoever is responsible for the operating system) can log onto his own virtual machine and go through the
generatien steps at his own pace while the daily work is being
processed. He can use the VM/370 CMS editor to create and update the job streams that are used during system generation. Whenever the system
generaticn Frccess requires, he can use CMS EXEC procedures to pass
these saved jeb streams to the test system. When the system is tested,
it can be placed online, replacing the previous version with minimal interruption to the production activity.
Fer a discussion of the CMS editor and EXEC facilities, refer to the CMS For details about the system generation
procedure for DOS/VS and as/vs under VM/370, refer to these
systell- dependent sections in this publication.
Creating VM/370 Directory Entries To allow a virtual machine to exist in the VM/370 system, the VM/370 system requires a directory entry definition. Each definition is kept
in a directcry entry source file (filetype DIRECt) on a user minidisk.
An installatien lIust use the VM/370 directory program to convert these
source definitions in the V"/370 systell directory file (usually on the
system residence disk) that contains one entry for each virtual machine.
Each directory entry contains a number of directory control
statements that define the virtual machine's configuration and other operational characteristics to VM/370. In general, a virtual machine
ccnfiguration defined in the directory consists of the following: • Virtual storage, console, and processor • Direct access storage devices • unit record devices • Other devices
Figure 13 shows the relationship of a directory entry to both the VM/370 system's real devices and the virtual machine's virtual devices.
The installation must keep both the source and system directories
updated. As users submit additions and/or changes, the installation must either create new or update current directory entries. This
updating can be done by using the VM/370 Directory Maintenance program
Product (5748-XE4), the CMS editor, or punched cards. (For more details
about this program product, refer to the GC20-1836.)
To create directory entries for operating systems running in virtual
machines, installations must consider both the general and unique
requirements for specifying directory entries. For general details
atout specifying directory entries, refer to fl!ftftiftg !ftQ For uniqup. details about specifying directory entries
fer operating systems running in a virtual machine, refer to the
fcllowing tepic "Unique Directory Entry Considerations."
36 IBM V5/370 Operating Systems in a Virtual Machine

VM!370 Directory Source File j (fn DIRECT fm)
By using the directory program, an installation converts sou rce
statements into the
VM!370 system
directory file. VM/370 Directory Entry USER DOSUSER DOSPWORD 320K CONSOLE 01F 3215 SPOOL OOC 2540 R , SPOO L OOD 2540 P , SPOOL OOE 1403 J MDISK 13033301 100 VMPK01 MDISK 131 33302050 VMPK02} MDISK 13233307030 VMPK02 DEDICATE 007 007 VM/370 Storage r---, I Virtual I Storage I I I 320K I i L __ ..J I Virtual Console I I Virtual Card Reader ( OOC I I I L ____ ..J Virtual Card Punch rOOD I L ____ --1 Virtual Printer I "" __ - --' J Real Device Dedicated
to DOSUSER Figure 13. Relationship of VM/370 Directory Entries
Section 1. General Considerations 39