Returns the value of the kernel variable that specifies the amount of free space to leave in the heap after full GC.

new-value---The requested new lisp-heap-gc-threshold.

Sets the value of the kernel variable that specifies the amount of free space to leave in the heap after full GC to new-value, which should be a non-negative fixnum. Returns the value of that kernel variable (which may be somewhat larger than what was specified).

Tries to grow or shrink lisp's heap space, so that the free space is (approximately) equal to the current heap threshold. Returns NIL

arg---a generalized boolean

Enables the EGC if arg is non-nil, disables the EGC otherwise. Returns the previous enabled status. Although this function is thread-safe (in the sense that calls to it are serialized), it doesn't make a whole lot of sense to be turning the EGC on and off from multiple threads ...

Returns T if the EGC was enabled at the time of the call, NIL otherwise.

Returns T if the EGC was active at the time of the call, NIL otherwise. Since this is generally a volatile piece of information, it's not clear whether this function serves a useful purpose when native threads are involved.

Returns, as multiple values, the sizes in kilobytes of the thresholds associated with the youngest ephemeral generation, the middle ephemeral generation, and the oldest ephemeral generation

generation-0-size---the requested threshold size of the youngest generation, in kilobytes

generation-1-size---the requested threshold size of the middle generation, in kilobytes

generation-2-size---the requested threshold size of the oldest generation, in kilobytes

If the EGC is currently disabled, puts the indicated threshold sizes in effect and returns T, otherwise, returns NIL. (The provided threshold sizes are rounded up to a multiple of 64Kbytes in CCL 0.14 and to a multiple of 32KBytes in earlier versions.)

arg---a generalized boolean

Tries to influence the GC to retain/recycle the pages allocated between GCs if arg is true, and to release them otherwise. This is generally a tradeoff between paging and other VM considerations.

Returns T if the GC tries to retain pages between full GCs and NIL if it's trying to release them to improve VM paging performance.