In either Faging or nonpaging mode, VS1 avoids using: • ISK (insert storage key) and SSK (set storage key) instructions;
instead, VS1 uses a protection key table • Seek separation for 2314 direct access devices • The ENABLE/DISABLE sequence in the VS1 I/O supervisor (lOS) • TCH (test channel) instructions preceding SIO instructions • PCI (pregram-controlled interruptions) in the BTAM autopoll CCi sequence
In nonFaging mode, VS1 with handshaking avoids using: • LRA (lead real address) and RRB (reset reference bit) instructions
(this is especially important when virtual machine assist is not
enabled) • The DIAGNOSE code X'10' instruction to release virtual pages or
discontiguous storage • VS1 paging and CCi translation
IBM 3850 MASS STORAGE SYSTEM CONSIDERATIONS There are no special system generation requirements when generating OS/VS (OS/VS1 or OS/VS2 MVS) to use the MSS and operate in a virtual
machine. Any VS1 or MVS system that supports the MSS can use VM/370 MSS support. VM/370 MSS support allows a VS1 or MVS virtual machine to: • Use a dedicated mass storage control (MSC) port (or channel
interface) and dedicated 3330V devices
--and-- • Act as the host for the VM/370 communicator program communicates 3330V mount and demount orders and responses between the MSC and VM/370) Hewever, this sUFPort requires each 3330V address defined in OS/VS to be
identical te the 3330V address defined both to and to the virtual machine using it.
For details about how to generate V8/370 to support the MSS and to
install the VM/370 communicator program in either VS1 or MVS, refer to For details about how VM/370 communicates with the MSS and uses it as well as how to provide tackuF and recovery for MSS volumes, refer to For details about MSS initialization, refer to Generating OS/VS Under VM/370 This topic discusses the major steps for generating as/vs in a virtual machine under VM/370. While the following procedures are for generating VS1, they are similar enough to SVS and MVS procedures to be used as examFles. The primary difference between generating VS1 and SVS or MVS under VM/370 is VM/iS handshaking for VS1. Handshaking requires that a
user specify the VM option in the VS1 SCHEDULR macro instruction.
section 4. OS/VS in a Virtual Machine 115

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