Everything that happens on a micro-controller has to be known. This includes dealing with memory. Many people (myself included) have developed a wonderful set of code that can dynamically use and free memory through the standard malloc and free functions. Only later do we discover that our available memory is getting reduced as time goes by -- followed by undetermined and random failures.
This is because no microcontroller (the included) has the ability to garbage collect.
For instance, let's say you malloc A and then malloc B. You then free A. There is now a memory hole (the size of A) that will never be closed again. Essentially a non-existing A is now taking up memory. If you now malloc A again, it will not be stored in that hole -- new memory will be taken up. You can see how this can become a problem.
Documentation of ReMem can be found here. Basically ReMem creates an object (with a specified size) that has two functions: rmalloc and free. These work exactly the same way as the conventional malloc and free except when you free data, it will be used again if the same size data is requested. (The disadvantage is that it can be slow, and takes an extra byte of data per malloc).
The code is currently stable, but I'm going to be adding the ability to reclaim data that has been freed at the end, as well as cannibalize large allocations. Stay tuned.
I have a new, more tested library for this purpose called tinymem. Check it out here: https://github.com/cloudformdesign/tinymem