[feature suggestion] Please allow to allocare memory dynamically

[Yuri]

The current behavior is that there is a fixed heap size, and the program pre-allocates that much memory. It later fails with the "Heap exhausted" error when it actually needs more memory than that limit. '--dynamic-space-size {limit}' is a relevant argument that allows to change the memory limit.

Problem: the user needs to guess how much memory the program would need. This is (1) very inconvenient, (2) is different from how most programs allocate memory.

Suggestion: Add a way for the program to allocate more memory as it needs it and only fail when the memory is really exhausted. For example, make '--dynamic-space-size auto' can do it.

Ideally auto memory allocation should be a default.

[Stas Boukarev (stassats)]

Having a non-contiguous dynamic space will complicate a lot of things and slow down the GC. And reserving a large chunk of memory will not play well with any non-lisp code that coexists in the same process.