Page of GC20-1801-10 As Updated April 1, 1981 by TNL GN25-0837
6. Any modifications to local OPTIONS COPIFILE, unless otherwise
specified in existing documentation, is not supported.
7. If an installation is using an IBM 3031, 3032, or 3033 processor,
it must dedicate the service record file (SRF) device to VK/370. Thus, the channel on which the SRF is located cannot be dedicated
to any virtual machine.
8. When using the SPOOL, DEDICATE, and SPECIAL directory control
statements to define virtual devices, specify virtual addresses
that do not conflict or content with the virtual control unit
interface. This conflict or contention occurs because devices can
require special I/O interface protocol from control units such as
shared and nonshared subchannel operations. Putting devices that
require different real control units on the same virtual control
unit can result in a hung or busy condition. To avoid this
problem, users must define (and separate) devices within their own
control unit range. For example, if the directory entry specifies: SPOOL 102 3211 SPECIAL 103 3270
The control unit 0 on channel 1 controls both a nonshared device
(the 3211 printer) and a shared device (the 3270 display unit).
Processing of channel programs involving these two devices can
result in a hung or busy condition.
9. The number of virtual devices for a virtual machine cannot exceed
the value determined by (7FFF/VDEVSIZE), where VDEVSIZE is the size
of the VDEVBLOK. If a greater number of virtual devices is
specified, results may be undesirable.
10. programs developed using CMS/DOS may not be transferable directly
to a DOS machine. The following considerations should be kept in
mind: • The CMS/DOS linkage editor is designed to linkedit DOS programs
for execution under eMS/DOS only. Programs transferred to a DOS machine should be re-link edited under DOS. • Programs assembled using CMS assembler may have incorrect ESDs. This is because the CMS assembler is not compatible with the DOS assembler. Programs transferred to a DOS machine should
therefore be re-assembled under DOS. Appendix F: VM/370 Restrictions 441

Ii 1:'''' .L.L I , 1:7 0 I 442 IBM VM/370 Planning and System Generation Guide