trimcore/0 reclaims space in all of Prolog's data areas. At any
given time, each data area contains some free space. For example, the
local stack space contains the local stack and some free space for
that stack to grow into. The data area is automatically expanded when
it runs out of free space, and it remains expanded until
trimcore/0 is called, even though the stack may have shrunk
considerably in the meantime. The effect of trimcore/0 is to
reduce the free space in all the data areas as much as possible, and to
endeavor to give the space no longer needed back to the operating system.
The system property
PROLOGKEEPSIZE can be used to define a lower bound on the amount
of memory to be retained. Also, the system property
PROLOGINITSIZE can be used to request that an initial amount of
memory be allocated. This initially allocated memory will not be touched
by trimcore/0.
When trimming a given stacks, trimcore/0 will retain at least
the amount of space initially allocated for that stack.
trimcore/0 is called each time Prolog returns to the
top level or the top of a break level, except it does not trim the stacks then.