Yes, but does any implementation actually do that? AFAIK Ada is typically more flexible, but that has to do with the language actually giving you enough facili

Yes, but does any implementation actually do that? AFAIK Ada is typically more flexible, but that has to do with the language actually giving you enough facilities to avoid heap allocations in more cases - e.g. you can not only pass VLAs into a function in Ada, but also return one from a function. So it becomes idiomatic, and compilers then have to support this (usually by maintaining a second "large" stack).