Unused RAM

[biolizard89]

If I need a somewhat large amount of unused RAM (let's say 1-2KiB) for use by a code, how would I do that?  I assume I would get a hex dump of the RAM and look for 1-2KiB of 00's, but do most games have at least some RAM space that is totally unused and safe to mess with?  I worry that the memory allocation routines in the game will eventually overwrite my data.  I suppose I could test this by setting a read/write breakpoint at that block, but how do most games work?  Will most games have a single contiguous block of RAM that is always safe to mess with, or will I have to use pointers/conditionals/other miscellaneous trickery to get that storage?

Thanks!