Desired maximum lifetime of a persistent connection.
	When set, Squid will close a now-idle persistent connection that
	exceeded configured lifetime instead of moving the connection into
	the idle connection pool (or equivalent). No effect on ongoing/active
	transactions. Connection lifetime is the time period from the
	connection acceptance or opening time until "now".

	This limit is useful in environments with long-lived connections
	where Squid configuration or environmental factors change during a
	single connection lifetime. If unrestricted, some connections may
	last for hours and even days, ignoring those changes that should
	have affected their behavior or their existence.

	Currently, a new lifetime value supplied via Squid reconfiguration
	has no effect on already idle connections unless they become busy.

	When set to '0' this limit is not used.