The "zone" is used as a reserve of stack memory for: 1. nominal host code stack usage. 2. stack space for error handling. 3. initial stack space for pushing VMEntrySentinel frames. The "zone" may reside on the C stack and on the C loop JSStack depending on context. Hence, the name "host zone" is not quite accurate, and we'll rename it to "reserve zone". Patch coming.
Make that "reserved zone".
Created attachment 220765 [details] the patch.
Thanks for the review. Landed on the jsCStack branch in r161582: <http://trac.webkit.org/r161582>.