JaB ENTRY AND OUTPUT RETRIEVAL When running QS/VS in a'virtual machine, a primary consideration is job
entry and Several techniques can be used for these
functions: • Use the OS/VS virtual machine in batch mode where it operates as OS/VS in native mode. It reads in job streams through a dedicated
card reader and prints output generated by the virtual machine on a
dedicated printer. • A single directory entry (userid) can contain a configuration
sufficient for running both and OS/VS (the alternating
technique). Load CMS to create and edit as/vs job streams and to
check the as/vs output. Load as/vs to run the as/vs job streams. • Use two different userids to keep two virtual machines running.
(This is the optimum environment.) Use one userid for the OS/VS machine while using the other for a CftS machine to create job streams
and inspect output. By using the CP DISCONN command, users can run
both virtual machines from the same terminal. Thus, both machines
are running concurrently, but a user communicates with only one at a
time. If two· terminals are available, each system can run
independently of the other.
Loading OS/VS At legan, use the userid for running as/vs. It lIay be a user's own userid when running alternating or concurrent systems. It may be a special userid that an installation has set aside exclusively for the OS/VS machine.
logon osvs
Because extended control (EC) mode is required to operate CS/VS, the
directory entry should contain the ECMaDE specification on the OPTICN control statement. If it is not included, enter this CP command to
enatle extended control mode simulation:
set eCllode on !Qte: To run OS/PCP and OS/MFT, a user does not need the ECMODE option.
To run OS/MVT, a user does not need the ECMODE option unless running the
generalized trace facility (GTF) under OS/MVT. However, OS/PCP, and OS/MVT normally required the REALTIMER option.
At this point, between logging on and loading the operating system, a
user may find it desirable or necessary to alter the virtual machine's
storage size. For exam FIe: If the directory entry specifies 1 megabyte
of storage and a user needs 2 megabytes for this particular terminal
session, issue the CP DEFINE command:
define storage as 2m Virtual machine storage can be redefined up to the limit set in the USER central statement of the directory entry. Once the IPL volume is made available, enter this command to load
as/vs:
ipl 250 Section 4. as/vs in a Virtual Machine 129

as/vs responds with a "SPECIFY SYSTEK PARAMETERS" message. The proper
use of a system Farameter list (IEASYSOO or IEASYSxx), created during or
subsequent tc the as/vs system generation process, can result in a
significant saving of time. Commonly used operator commands can be
placed in the SYS1.PARKLIB data set to shorten the IPt process. OS/VS Operation
To control OS/VS, use OS/VS operator commands to hold and release queues
and jobs and to start initiators or define partitions. Users can
otserve the progress of the command's execution by following the as/vs
messages. Figure 18 shows how VK/370 loads VS1 in a virtual machine.
r-------------------------------------------------------------------------, LOGON AT 01:96: 14 EST WEDNESDAY 10/29/75 def stor 3012k STORAGE = 03072K q set MSG ON , iNG ON , EMSG TEXT , ACNT ON , RUN OFF LINEDIT ON , TIMER REAL , ISAM OFF , ECMODE ON ASSIST ON SVC , PAGEl OFF , AUTOPOLL OFF IMSG ON , AFFINITY OFF def 009 01f CONS 01F DEFINED
q chan CHANNELS = SEL def chan blRx CHANNELS = BMX The virtual selector channels have been redefined
to block multiplexer. This is a performance
consideration to improve the of I/O operations. To avoid issuing the CP DEFINE command, the VM/370 directory entry can specify
the BMX option in the OPTION control statement.
Figure 18. Sample IPL of VS1 under VM/370 (Part 1 of 2) i30 IBM VM/370 operating Systems in a virtual Machine