An integer between 0 and 7, inclusive.
An integer greater than 12800, or a real in the inclusive range [0 100], or
sets the threshold for additional allocation that triggers a garbage collection (GC) in generation
when this is the blocking generation (as set by set-blocking-gen-num). A GC is triggered when the allocation in generation
grows more than
over the allocation after the last GC of this generation (or a higher generation).
To set the threshold, threshold can be an integer greater than 12800, which is interpreted as the absolute value. Alternatively threshold can be a real number in the inclusive range [0 100], which is multiplied by the allocation since the previous GC to get the actual threshold to set.
can be called when the generation
is not the blocking generation, and will set the value for that
. Such a call will not take effect until the generation
becomes the blocking generation, as set by a call to set-blocking-gen-num (with