When running DOS/VS disconnected, VM/370 ignores all output or "writes" tc the virtual console unless the console is spooled. To spool virtual
ccnsole a virtual machine user can issue the following CP command befcre disconnecting the virtual machine: #cp sFcol console start
This command starts recording all console output on a spool file. When the user logs on again, he can issue:
spool console stop close
This command stoFs console spooling and releases the spool file to the
real printer. If this command is not entered, VM/370 saves all spooled
ccnsole outFut except the last 4K page of output. Developing and Testing Programs to Run In a DOS/VS Virtual Machine
The foregoing discussions noted how to use the eMS editor and the EXEC facility tc help Frepare jobs for execution in a DOS/VS virtual
machine. In addition tc these CMS features, there are a number of other CMS commands for developing and testing programs on CMS disks. One advantage of storing source programs on CMS disks is that they can be
maintained as backup cOFies of a program while a second version is being
tested and debugged. CMS has a specia I e nvironmen t, called CMS/DOS, which provides many
commands that simulate the functions of DOS/VS or DeS/VSE if VM/370 Basic Systea Extensions Program Product (5748-118) is installed. An installation needs this program product for VM/370 to support FE-512
devices in its configuration. (For DOS/VSE to access FE-512 devices, an
installation also needs to install the VSE/VSAM program Product, Program NO. 5746- A M 2 ) Some of the things that can bs done in CMSjDOS are: Creating eMS macro libraries from DOS/VS assembling programs directly in CMS. (Assembler
are disFlayed on the terminal.) macro libraries and
diagnostic messages Compiling Frograms written in DOS/VS COBOL or DOS/VS PL/I programming
languages, using DOS/VS macro libraries. Displaying or printing the directories of DOS/VS private or system
core image, relocatable, source statement, or procedure libraries. Displaying or Frinting the procedure library. Link-editing TEXT decks from eMS disks, or relocatable modules from DOS/VS or Frivate relocatable libraries. These simulated core image
libraries called DOSLIBs are on a CMS disk. Users can also copy
relocatable modules from DOS/VS libraries. Loading core image phases from CMS DOSLIBs or from DOS/VS core image
libraries into virtual storage and executing them. Identifying system and programmer logical units for programs being
used and listing current assignments. 104 IBt'5 VM/370 operating Systems in a Virtual Machine
Identifying disk files. When executing programs in CMS/DOS, users
can read sequential disk files directly from DOS disks, but cannot
write on them. Instead, for testing purposes, write disk files
or output files to the virtual punch or printer, or to a tape. An exception to this rule is when executing COBOL and PL/I programs in CMS/DOS. eMS can be used to both read and write VSIM files located
on DOS disks. Using the CMS and VM/370 debugging facilities to debug a program
under CMS. Users can set address stops (called breakpoints in the CMS debug environment) and temporarily halt the execution of a program to
examine or change the contents of registers or specific storage
locations. When a is
prepare a jcb stream
virtual machine.
tested and debugged in CMS/DOS, users
to catalog and execute the program in
can also
a DOS/VS For cOMplete details about how to use CMS/DOS, refer to User's Guide. For details about how to specify CMS commands, refer to Summary When a virtual machine user loads DOS/VS into his virtual machine, the
terminal beccmes the DOS/VS operator console, and the virtual machine
user becomes the operator responsible for entering all commands and
respcnses. The three basic techniques for using DOS/VS in a virtual machine are: running DOS/VS in batch mode, using the IPL command to
alternate between DOS/VS and eMS in a single virtual machine. and
running DOS/VS disconnected.
Before using cne of these techniques, an installation must understand
how to: Generate DOS/VS to run in a virtual machine create VM/370 directory entries for DOS/VS virtual machines Access the DOS/VS system residence volume Ensure that the proper I/O devices are attached to the DOS/VS virtual
machine IPL and operate DOS/VS under VM/370 The primary objectives when generating DOS/VS to run in a virtual machine should be to avoid double ccw translation and to reduce the
number of SID instructions issued by DOS/VS. To meet these objectives,
an installaticn needs to consider how it generates both VM/370 and DOS/VS.. (DOS/VS can be generated under VM/370.) DOS/VS oFeration depends upon how DOS/VS was generated. There may be
additional cperator commands and control statements that must be entered
at the ccnscle before running jobs on the DOS/VS virtual machine. There are many that DOS/VS virtual machine users can be helped
by using the CMS component of VM/370. The CMS editor and EXEC facility
can be used to prepare jobs for execution in a DOS/VS virtual
machine. CMS commands can be used to develop and test programs on disks. The CMS/DOS environ.ent provides many commands that simulate DOS/VS functions. Section 3. DOS/VS in a Virtual Machine 105
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