Constant DEBUG_FRAME_STACK_SLOTS 

pub const DEBUG_FRAME_STACK_SLOTS: usize = _; // 8_001usize

The size of the debug frame-entry reservation, in slots — one per live call, bounded by the same depth guard, plus one entry of headroom for the Rust-side push_frame callers, who spend no budget and so are not covered by that guard. This is SHADOW_STACK_SLOTS’ headroom term counted in frames, because a frame stack claims one entry per call rather than one per slot.