Well, Android isn't "just Linux", if that were the case it wouldn't be able to run any Android apps. Anyway, it's my understanding that Android uses custom hea

Well, Android isn't "just Linux", if that were the case it wouldn't be able to run any Android apps. Anyway, it's my understanding that Android uses custom heap size limits to help keep things running smoothly. This combined with efficient garbage collection makes for a generally smooth user experience on a constrained device like a phone or tablet. Android will cache, and later kill, processes that aren't being used, to free up memory for active processes. Memory may be a finite resource, but not in the way you described; it's not permanently used up and can always be freed for foreground tasks.