Function create_mspace_with_base 

pub unsafe extern "C" fn create_mspace_with_base(
    base: *mut c_void,
    capacity: usize,
    locked: i32,
) -> *mut c_void

`create_mspace_with_base`` uses the memory supplied as the initial base of a new mspace. Part (less than 128*sizeof(size_t) bytes) of this space is used for bookkeeping, so the capacity must be at least this large. (Otherwise 0 is returned.) When this initial space is exhausted, additional memory will be obtained from the system. Destroying this space will deallocate all additionally allocated space (if possible) but not the initial base.