pub const STACK_BYTES: usize = _; // 67_108_864usizeExpand description
The host stack the front end needs to reach MAX_NESTING on every one of its recursions.
Declared rather than discovered, and held to the ceiling by a test in each crate that recurses
(beck-syntax, beck-core) which measures bytes per level and fails if the declaration has
stopped covering it — the pair beck-eval has had since docs/31 §31.3, for the same reason
and against the same failure.
It is deliberately the same 64 MiB beck_eval::STACK_BYTES declares, because the two are
consumers of one thread: beck-cli compiles and evaluates on the stack it dispatches onto,
and the_front_end_fits_the_stack_the_cli_gives_it is what keeps the two numbers honest about
each other. They are not summed: a compilation has finished reading before it begins running.