Constant DEFAULT_ARENA_CAPACITY 

pub const DEFAULT_ARENA_CAPACITY: usize = _; // 2_147_483_648usize

Default stream arena capacity.

2 GiB of virtual address space per arena. With Vec64/MAllocPg64 backing, physical memory is committed only as bytes are written, so the reservation is cheap under normal Linux overcommit. Each stream decoder and, under the arena feature, each file reader holds one arena.