number
Directory Program is a one-to eight-character account number that is punched in
the accounting data for this virtual machine. The USERID from
the USER statement is also punched in the accounting data.
distribution
is a one-to eight-character distribution identification word
that is printed or punched with the userid in the separator
for spooled output for this user. This value is optional and
defaults to the userid from the USER statement if oJllitted.
The OPTION control statement selects specific options available to the
user. This statement is optional and, if used, must follow the USER statement or another OPTION statement, and precede the first device
statement (CONSOLE, "DISK, DEDICATE, LINK, or SPOOL) • Multiple OPTION statements can be inserted if the options selected exceed the statement
record length. The -format of the OPTION control statement is: r----· , Option Realtimer Ecmode Isam Virt=real Acct Svcoff BMX , CPUID bbbbbb AFFinity nn L- REALTIMER provides a timer for the virtual machine that is updated
during virtual processor run time and also during virtual wait
time. (If the virtual machine does not have the REALTIMER
option, its timer reflects only the virtual processor run time
used.) This option is required for virtual machines running
systems or programs that go into a wait state expecting a
timer interruption. This timing ability can also be obtained
by issuing the CP command line SET TIMER REAL. ECMODE allows the virtual machine to run in extended control mode.
The ECMODE option must be specified for virtual machines using
operating systems that:
1. Operate in System/370 extended control mode (such as VM/370 itself).
2. Use the dynamic address translation facility (such as OS/VS1, OS/VS2, DOS/VS, and VM/370). 3. Use control registers other than zero
(General Trace Facility), which uses
requires control register eight) • 4. Depend on
feature.
the System/370 extended
(such as OS GTF Monitor Call and
channel masking
The ECMODE option must also be specified for the virtual
machine that is to perform system support or updating, and for
an RSCS virtual machine. ECMODE is also required when using
the clock comparator.
Note: A virtual machine defined without the ECMODE option in
the-directory is limited to 6 I/O channels, while a virtual
machine with the ECMODE option may address up to 16 I/O Part 2. Defining Your VM/370 System 203

Directory Program ISAM channels. If a virtual machine with the option
executes in basic control mode, the I/O masking for channels 6
and higher is simulated by the extended channel feature. If a
virtual machine with the EC"ODE option executes in extended
control mode, the I/O masking for all 16 channels is handled
via extended control register 2. This facility can also be
obtained by issuing the CP command SET EC"ODE ON. provides special channel command word translation routines
that permit as/pcP, "FT, and MVT ISA" programs (which
dynamically modify their CCis) to operate properly in a
virtual machine. This is required only for virtual machines
that use as/pcP, or MVT ISAM access methods or OS/VS ISA" when executing in a V=R partition under OS/VS. This option is
not needed for DOS, DOS/VS, or OS/VS ISAM when run only in a V=V partition of OS/VS. This facility can also be obtained by
issuing the CP command SET ISAM ON. VIRT=REAL is a performance option that allows the user to place his
virtual machine in lower storage. such that its virtual
storage addresses correspond to the real storage address
(except for its page zero, which is relocated). The real page ACCT SVCOFF zero is controlled by the CP nucleus. No CCi translation is
required. This option is required for a virtual machine to
successfully execute self-modifying channel programs other
than those generated by OS/VS TCAM (Level 5, generated or
invoked with the VM/370 option) or OS ISAM. VIRT=REAL can be
specified for any number of virtual machines but only one
virtual machine can use this facility at any given time. A
named or shared system cannot be loaded (via IPL) in a
virtual=real area. The device address must be specified in
the IPL command. To generate a VM/370 system with a
virtual=real machine, see "Specifying a Virtual=Real Machine" in the Part 1.
a user with the ACCT option in his directory can charge
another user for virtual machine resources. For example, a
user who sends a job to the CftS batch virtual machine can be
charged for the time that he uses in the batch machine. Note
that the ACCT option should be specified in the directory of
the CftSBATCH virtual machine so that user/job identifying
information will be printed on the forms separator that
separates spooled output files.
specifies that CP, instead of the virtual machine assist
feature or the V"/370 Extended Control - Program Support handles all SVC interrupts for this virtual machine. A user
whose directory entry contains this option can override it by
issuing SET ASSIST SVC. All SVC 76 interrupts are handled by CP whether or not
the SVCOFF option is specified. BftX specifies that all virtual machine I/O operations are to occur
as block multiplexer channel operations rather than selector
channel (the default) operations. In block multiplexer mode, the virtual channel is not busy until the initial 510 is
complete (selector mode operates similarly). Block
multiplexer allows the successful start of multiple SIOs to
different devices on the same channel. However, virtual I/O operations on channel 0 are processed as byte multiplexer
channel operations. Channels that have a channel-to-channel
adapter are restricted to selector channel operation. 204 IBft VM/370 Planning and System Generation Guide