Name: httpkeepalive
Type: DURATION
Default-Value: 20s
Last-Modified: 3.1.8

Set the length of the HTTP server's keepalive heartbeat.  The default is 20
seconds.  The minimum value is 0, which will disable the keepalive
heartbeat.  When enabled, if a request takes longer than *httpkeepalive* to
process, the server will send the client provisional responses every
*httpkeepalive* until the final response can be sent.

For backward compatibility, if no unit is specified, seconds is assumed.
