z/VM: CP Commands and Utilities Reference - z/VM - IBM

SET RUN
►►
Set
RUN
Authorization
Purpose
Operands
ON
OFF
Usage Notes
Privilege Class: G
Use SET RUN to control whether your virtual machine runs while a CP-initiated
read is outstanding at your terminal.
ON
OFF
When RUN is set ON, the following differences in virtual machine management
occur:
1. If your virtual machine is runable, it processes instructions even if a
CP-initiated read is outstanding at your terminal
SET RUN
2. CP does not automatically begin another terminal read when an outstanding
read is satisfied
3. If none of your configuration virtual processors are runable, CP does not
automatically begin a terminal read.
Initially, RUN is set OFF for all users except the primary system operator.
RUN may not be set ON after a trace trap has been established in an active
trace set unless the trace set is suspended. This ensures that the virtual
machine is not running during the terminal read that may result when a trace
trap springs. Similarly, RUN is automatically set OFF when a trace trap is
established in a non-suspended trace set.
1. An outstanding CP-initiated read does not necessarily indicate that your virtual
machine is not executing instructions. When RUN is set ON, your virtual
machine may process even with a CP-initiated read outstanding.
2. The SET RUN command allows the operator of a second-level system operating
in full-screen mode to press the break key and enter CP commands without
unnecessarily delaying the instruction execution of users of that second-level
system. Note that when your terminal is operating in line mode, the same effect
can be achieved by entering CP commands preceded by #CP, where #
represents your logical-line-end character.
3. If your virtual machine is not runable (for example, it is in a stopped or
disabled-wait state), and RUN is set OFF, CP initiates a terminal read. On
locally connected terminals and logical devices, this prevents CP from writing
messages sent to the user ID. In this situation, RUN can be set ON to prevent
CP from initiating the read; this keeps the terminal free for incoming messages.
4. Some CP commands prevent the virtual machine from running until all terminal
output associated with the command has been displayed. If the output is
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Chapter 2. CP Commands 1375