[gambit-list] malloc/free vs ___EXT(___alloc_rc)/___release_rc

Hi, I'd like to know what's the main difference between using the malloc/free combination vs. the ___EXT(___alloc_rc) / ___EXT(___alloc_rc) one. Mi intention is to create C arrays and manage them from the Scheme side, so I can explicitly free them once I need to. Which one should I use? Thank you, Álvaro