Attempts to promote all objects from generation zero into generation one, thereby clearing generation zero.
clean-generation-0 => 1
Returns the value 1.
This is useful when passing from a phase of creating long-lived data to a phase of mostly ephemeral data, for example, the end of loading an application and the start of its use.
; allocate lots of non-ephemeral objects
LispWorks Reference Manual - 6 Apr 2005