pub const JS_STACK_SIZE: usize = _; // 268_435_456usizeExpand description
Stack reserved for the thread JS runs on (run_on_js_stack).
A JS call is a Rust recursion (host::run_user_func_nt → run_chunk_on →
a fresh fusevm::VM on the stack), so recursion depth is bounded by the
native stack rather than by a frame counter. On the OS default 8 MiB this
bought only 83 frames in a debug build — measured, node -e 'function f(n){if(n<=0)return 0;return 1+f(n-1)} f(84)' aborted — where node v26.7.0
reaches 9901. Reserving 256 MiB is virtual address space, faulted in only as
deep recursion actually uses it, and host::stack_exhausted still turns the
far end into a catchable RangeError rather than an abort. The reservation
is capped rather than sized to match node’s depth exactly so that a runaway
recursion’s peak RSS stays bounded; the resulting depth is documented in
BUGS.md.