For further information on system value QINACTITV, refer to document New, QINACTITV System Value Explained. The virtual device then goes into a SIGNON DISPLAY status and the user is presented with the sign-on screen. For named virtual devices (for example, PC52S1), the system value QINACTMSGQ defines what action is to be taken with the interactive job. For auto-selected virtual devices (for example, QPADEV0003), the interactive job is always ended. The QINACTITV value defines the length of time an interactive job can be in DSPW status before action is taken. Whereas the Telnet Session keep-alive parameter is used to detect and act upon clients no longer responding, the system value QINACTITV is used to act upon inactivity by the user (for example, user went to lunch still logged onto the session). Once action has been taken on the interactive job, the virtual device is recovered to a VARY ON PENDING status to allow a new connection. If it is a named virtual device, (for example, PC52S1), then the action specified in the system value QDEVRCYACN is taken. If it is an auto-selected virtual device (for example, QPADEV0002), then the interactive job is always ended. For Telnet, the recovery action depends on the type of virtual device associated with the user's interactive job. The Telnet server takes advantage of the TCP keep-alive functionality with its Session keep-alive parameter (TIMMRKTIMO). If the client does not respond to any of these requests, the protocol will assume the client is no longer active (for example, PC hanging or re-booting, network drop, and so on). If the client does not respond to the first request, the protocol will re-send the request until the client responds or until the tenth request has been sent.
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When the value in this parameter has been reached, the TCP protocol will send a TCP keep-alive request to the client.
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The TCP keep-alive parameter (TCPKEEPALV) specifies at which intervals the protocol begins to probe the client. The TCP protocol utilizes a mechanism to probe if the client is still active.