Function create_mspace 

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

create_mspace creates and returns a new independent space with the given initial capacity, or, if 0, the default granularity size. It returns null if there is no system memory available to create the space. If argument locked is non-zero, the space uses a separate lock to control access. The capacity of the space will grow dynamically as needed to service mspace_malloc requests. You can control the sizes of incremental increases of this space by compiling with a different DEFAULT_GRANULARITY or dynamically setting with mallopt(M_GRANULARITY, value).