Idiomatic Racket CS replacement for `scheme_malloc_code`?

Hi all,

I'm looking for the best idiomatic replacement for scheme_malloc_code in Racket CS.

Previously, I could run:

(define builtins (ffi-lib #f))
(define %scheme-malloc-code
  (get-ffi-obj "scheme_malloc_code" builtins (_fun (size : _long) -> (_bytes o size))))

... and use %scheme-malloc-code to get a callable, writable bytevector for sticking machine code in, plus the GC would clean it up if it became reclaimable.

Are there any (even rough) equivalents in Racket CS?

Best,
Tony