Constant BYTES_PER_RUNG 

pub const BYTES_PER_RUNG: usize = _; // 49_152usize

Stack reserved per rung of nesting past INLINE_DEPTH.

48 KiB is roughly three infer_type frames per rung of term depth, measured against a telescope that spends about one frame per rung. The reservation is virtual: Linux commits a thread stack page by page, so a deep term reserves address space and touches only what it uses.