> is there any standard custom memory allocator available?
> I was thinking to request a bigger chunk of memory in one shot from the
> system and later custom allocator will keep allocating and free memory
> chunk from that.
Try the K&R allocator. Google found a copy at
CS453-resources/tree/master/ examples/memory-management/ simple-malloc
If you want to find other copies, search for
"morecore: ask system for more memory"
You'll have to adapt morecore to your needs: for instance, by replacing sbrk.