April 1, 1981
Before the LOADSYS 320K r I l I I I All storage I Addressable by I virtual Machine I I I V OKL -J CMS Virtual Machine
without a Named Segment Attached
After LOADSYS Function
__ ____ _____ _ I I I Discontiguous Storage Addressable by Virtual Machine ./1111//1/////11111/1/11// • • /Storage Not Addressable/ • • lllby Virtual Machinel///. 111111111//1/1//11/1/11//. __ l I Storage Still Addressable by Virtual Machine I , eMS virtual Machine with
a Named Segment Attached Figure 24. Addressable Storage Before and After a LOADSYS Function When you save a named segment that is later loaded by the LOADSYS function, you must be sure that the addresses at which segments are
saved are correct and that they do not overlay required areas of storage
in the virtual machine. This is crucial because the LOADSYS function
invokes the function before it builds the new page and swap
tables. CP purges all saved systems that are overlayed in any way by
the saved system it is loadinq.
A condition code of 0 in the PSi indicates that the named segment was
loaded successfully; the Rx register contains the load address.
A condition code of 1 in the PSi indicates the named segment was
loaded successfully within the defined storage of the virtual machine.
The Rx reqister contains the address at which the named segment was
loaded. The Ry register contains the ending address of the storage
released before the named segment was loaded. MQte: CMS only allows named segments to be attached beyond the defined
size of the virtual machine.
A condition code of 2 in the PSi indicates the LOADSYS function did
not execute successfully. Examine the return code in the RV register to
determine the cause of the error. ReiY.t!l 44
177 ,t!ganing Named segment does not exist Paginq IIO errors 202 IBM VM/370 System Programmer's Guide

April 1, 1981 When the PURGESYS function is executed; CP releases the storage, and
associated page and swap tables, that were acguired when the LOADSYS function was executed. If the storage occupied by
the named segment was beyond the defined virtual machine storage size,
that storage is no longer addressable by the virtual machine. When a PURGESYS function is executed for a segment that was loaded in
nonshared mode, the storage area is cleared to binary zeros. If PURGESYS is invoked for a named segment that was not previously loaded
via LOADSYS, the request is ignored.
A condition code of 0 in the PSi indicates successful A condition code of 1 in the PSi indicates that the named segment was
not found in the virtual machine.
A condition code of 2 in the PSW an'd a return code of 44 in the Ry register indicate that the named segment either does not exist or was
not previously loaded via the LOADSYS function. When the FINDSYS function is executed, CP checks that the named segment
exists and that it has not been loaded previously.
A condition code of 0 in the PSi indicates that the named segment is
already loaded. The address at which it was loaded is returned in the register specified as Rx and its highest address is returned in the Ry reqister. A condition code of 1 in the PSW indicates that the named segment
exists but has not been loaded. In this case, the address at which the
named segment is to be loaded is returned in the register specified as
Rx and the hiqhest address of the named segment is returned in the Ry register. A condition code of 2 in the PSW indicates the FINDSYS function did
not execute successfully. Examine the return code in the Ry register to
determine the error that occurred. Retu£!l 44
177 t!eaning Named segment does not exist
paging I/O errors DIAGNOSE Code X'68' --Virtual Machine
Communication Facility (VMCF)
The DIAGNOSE Code X'68' is used by a virtual machine to initiate a
subfunction of the virtual Machine Communication Facility (VMCF). The
qeneral register specified as Rx contains the virtual address,
doubleword aligned, of a parameter list (VMCPARM). One of the entries
in this para-m-eter li-s-t -is a- - subfunctioIl-code, specifying the particular
request being initiated. The subfunctions and their codes are: Part 2. Control Program (CP) 203