In the DOS/VS in a virtual machine section, the alternating technique
(using one virtual machine and multiple alternating systems) was used to
generate DOS/VS. While convenient for DOS/VS where only one system
cculd be executing at anyone time, it is not a convenient technique for
generating OS/VS. OS/VS system generation runs are much longer, and
installaticns should use other methods that improve overall throughput.
In this two virtual machines are used to generate as/vs under VM/370. Figure 17 shows the directory entries for these two virtual
machines: OSVSSYS and OSCMS. The OSVSSYS virtual machine performs the majority of the system
generaticn steps. In addition to the devices specified in the directory
entry for user OSVSSYS, this user temporarily needs a dedicated tape drive at virtual address 181 on which to mount the starter system and
distribution library tapes. Attaching this tape drive is explained
later in this topic.
The OSCMS virtual machine is for preparing job streams for the OSVSSYS virtual machine, executing some steps in the system generation,
and scanning output from OS/VS. By using the CMS editor, a user can
create, store, and update the job streams used in the system generation
runs. At the various stages of generation, the user can (by using the VM/370 spool system and CP spool file commands) load the appropriate
jcb streams into the virtual card reader for OS/VS. USER OSVSSYS PASSWORD 768K ACCOUNT ACCTNO BIN16 OPTION ECMODE REALTIMER CONSOLE 01F 3210 SPOOL OOC 2540 R SPOOL OOD 2540 P SPOOL OOE 1403 MDISK 350 3330 0 404 DLIBA1 MR RPASS WPASS MDISK 351 3330 0 404 DLIBA2 MR RPASS WPASS MDISK 250 3330 0 404 OSVSYS MR RPASS WPASS USER OSCMS PASSWORD 320K ACCOUNT ACCTNO BIN16 CONSOLE 01F 3210 SPOOL OOC 2540 P SPOOL OOD 2540 P SPOOL OOE 1403 LINK CMSSYS 190 190 RR MDISK 191 3330 50 10 UDISK1 WR RPASS Figure 17. Virtual Machines for OS/VS System Generation PREPARING FOR OS/VS SYSTEM GENERATION
Before using the starter system and distribution system libraries for
system generation, do the following: • Initialize the voluaes (DLIBA1 and DLIBA2) that are to contain the
starter system and distribution • Restore the starter system from tape to a DASD volume (DLIB!1). 116 IBM V!/3 1 0 Operating systems in a Virtual

• Use the starter system to copy the distribution libraries from the
tape volumes (DLIBT1 and DLIBT2) to a DASD volume (DLIBA2). • Create stand-alone card decks for independent utilities. • List the VTOC of each current system volume (this listing can be used
when reallocating data sets in the future) • • Initialize the volume that is to contain the new OS/VS. The following examples in this topic assume that the two virtual
machines (whose directory entries were shown in Figure 17) each have
their own 3270 terminals. If two terminals are available, this is the
mcst efficient method. Each system (CMS and OS/VS) runs independently
with full terminal access.
However, a user can run the same procedures and use a single
terminal. For example: To access the OSVSSYS virtual machine, place
the osces virtual machine in disconnect mode and log onto CSVSSYS. The
disccnnected virtual machine (OSCMS) continues to run. When ready to
exchange virtual machines again, disconnect from the OSVSSYS machine and
log tack cnto osces. Logging back onto a disconnected virtual machine
stops its execution. To resume operation, enter the CP BEGIN command. !gte: Before using the disconnect method of running two virtual machines
from one terminal, note the disconnection considerations described later
in this section.
INITIALIZING THE STARTER SYSTEe VOLUeE The utility control statements supplied as card input on a stand-alone
system can be generated as ces files in a Ve/37C environment. The editor and EXEC facilities, along with the V5/370 spool file system,
allow a user to create, update, and store entire job streams or
individual job steps. Data as well as job control language statements
can be included in these ces files.
Fer example: A user can use the osces virtual machine
reader input required by the IBCDASDI utility program.
the DASD volume to contain the starter system, log
virtual machine, load CMS, and enter the following:
to create the
To initialize
onto the edit initstrt ojcl
input
(open and identify new file)
(enter input mode)
initvo11 job
msg todev=3210,toaddr=Oif dadef todev=3330,toaddr=350,volid=scratch,passes=0 vld newvolid=dliba1,ownerid=sysprogmr
vtocd strtadr=14,extent=5
end
(null line)
file
(to return to edit mode)
The IBCDASDI control statements now reside in a C8S file. They are
identified as INITSTRT OJCL and belong to the OSCMS virtual machine. Section 4. OS/VS in a Virtual Machine 117