SET RUN

Read syntax diagramSkip visual syntax diagram Set RUN ONOFF

Authorization

Privilege Class: G

Purpose

Use SET RUN to control whether your virtual machine runs while a CP-initiated read is outstanding at your terminal.

Operands

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
  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.

Usage Notes

  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 delayed, for example, because the screen enters "MORE..." or "HOLDING" state, then the virtual machine will not run. The SET RUN ON command does not affect this behavior.

    Similarly, virtual-machine I/O to the console will be queued during "MORE..." or "HOLDING" state, and the I/O completion will not be reported to the virtual machine until that state is cleared. If the virtual machine voluntarily enters wait state until its console I/O completes, then it will appear unresponsive until the "MORE..." or "HOLDING" condition is cleared.

  5. In some cases, SET RUN ON may not enable a user to keep running during a CP-initiated read, or a similar situation. For example, if a console I/O error occurs, the user will not continue to run, and will eventually be FORCED off the system if a DISCONNECT_TIMEOUT interval is set in the SYSTEM CONFIG file.

Messages

  • HCP003E Invalid option - {option|command contains extra option(s) starting with option}
  • HCP026E Operand missing or invalid
  • HCP1031I SET RUN ON is not allowed when the trace function is active.