Paqe of GC20-1807-7 As Updated April 1, 1981 by TNL GN25-0829 UNAUTHORIZE terminates VHCF activity for a virtual machine. The UNAUTHORIZE subfunction causes any stacked or queued messages associated
with the virtual machine to be purged. A virtual machine should execute
the QUIESCE subfunction before executing UNAUTHORIZE if messages that
are already queued are to be handled. When a virtual machine executing UNAUTHORIZE has pending final response external interrupts, 'the
interrupts are purged. If a virtual machine has pending SEND external
interrupts from another source virtual machine, a RESPONSE interrupt is
reflected to the source indicating that the virtual machine is no longer
available. CANCEL cancels a message or data transfer pending for but not accepted
by another VMCF virtual machine. A virtual machine can CANCEL ·messages
it oriqinates with SEND, SENDX, or SEND/RECV subfunctions. A message
cannot be canceled if any of the following conditions exist: • The request was SENDXor IDENTIFY and the sink had already received
the SEND external interrupt. • The request was SEND and the sink had already executed the RECEIVE or REJECT subfunctions. • The request was SEND/RECV and the sink had already executed the REPLY or REJECT subfunctions.
If the original request was SEND/RECV and the sink virtual machine had
executed the RECEIVE subfunction but not the REPLY, the REPLY can be
canceled. A virtual machine is notified of this condition with a DIAGNOSE return code. (For a description of the return codes, see
Figure 19). QUIESCE temporarily rejects SEND, SENDX, SEND/RECV, or IDENTIFY requests
from other virtual machines. QUIESCE allows a virtual machine to
receive any stacked or queued messages but reject further SEND, SENDX, IDENTIFY, or SEND/RECV requests from other virtual machines. QUIESCE can be used to indicate to other virtual machines that the virtual
machine is in QUIESCE status, authorized for communication but not able
to accept messages at this time (e.g., entering slowdown, my buffers are
full, tryaqain later). The IDENTIFY subfunction could be used to
inform other virtual machines that a particular user is no longer in QUIESCE status. You should execute the QUIESCE subfunction before
executing the UNAUTHORIZE subfunction to avoid losing messages (see "UNAUTHORIZE: DIAGNOSE Code X '68' Subfunct"ion Code X· 0001"')... A virtual
machine can reset the OUIESCE status (exit slowdown) by executing the RESUME subfunction. (See "RESUME: DIAGNOSE Code X'68' Subfunction Code X'0009'''). A virtual machine in QOIESCE status may continue to send
messaqes to other virtual machines. QUIESCE status for a virtual
machine only affects messages sent from other virtual machines.
154 IBM VM/370 System Programmer's Guide

RESUME cancels the QUIESCE status, allowing your virtual machine to
resume reception of YMCF requests from other virtual machines. You can
use the IDENTIFY subfunction to inform other virtual machines that your
virtual machine is no longer in QUIESCE status. (see "IDENTIFY: DIAGNOSE Code X'68' Subfunction Code X'OOOA'"). IDENTIFY notifies another virtual machine that your virtual machine is
available for YMCF communication. Use the IDENTIFY subfunction after
issuing the AUTHORIZE subfunction or after your virtual machine has been
in the VMCF QUIESCE state and you have issued the RESUME subfunction. IDENTIFY causes an external interrupt to be stacked for a specified
virtual machine. The virtual machine executing the IDENTIFY subfuncticn
specifies the userid of the user to receive the external interrupt.. The
external interrupt identifies the virtual machine executing the IDENTIFY subfunction. The IDENTIFY subfunction is provided to inform a host or
controller virtual machine that a virtual machine is activated (logged
on) and ready for VMCF communication. The IDENTIFY subfunction can also
be used to inform other virtual machines that ycur virtual machine has
exited QUIESCE state. There is no response external interrupt
associated with the IDENTIFY subfunction.
The IDENTIFY subfunction can also be used to pass virtual machine
defined control information. The fields in the VMCF parameter list (VMCPARM) not used by the IDENTIFY subfunction may be used to contain
additional virtual machine data.
REJECT selectively rejects pending SEND or SEND/RECV requests from other VMCF virtual machines. REJECT causes a response external interrupt to
be reflected to the originator of a message. The external interrupt
indicates to the originator that the message was rejected. The user
doubleword within the external interrupt header may tell a user why the
message was rejected. When the user of a virtual machine executes the
REJECT subfunction, he specifies within the YMCF parameter list (YMCPARM) the message ID of the message to be rejected. A virtual machine cannot reject a message sent with the SENDX subfunction since
the message is received at the same time the external interrupt is
received. The REJECT subfunction can be executed as response to either SEND or SEND/RECY requests.
THE DATA TRANSFER FUNCTIONS The data transfer operations are SEND, SEND/REeV, SENDX, RECEIVE, and REPLY. These operations involve the movement of data from one virtual
machine storage to another virtual machine storage. Part 2. Control program (CP) 155