Function set_arena_bytes 

pub fn set_arena_bytes(bytes: usize)

Override the wasm arena reservation size, in bytes. Must be called BEFORE the first compile() — the region is reserved on first use and then fixed, so a later call has no effect. 0 disables the arena entirely (every allocation forwards to the system allocator: lower memory, slower). No effect on native targets (they always use the 2 GiB virtual reservation).