Memory leaking and embedded linux

I am running my own c++ program in embedded linux. At first VSZ is ~6000kB (top) but after 1h VSZ is increased ~100kB. In the program there is two threads. Both threads take tcp and ssl connections almost all the time. I have run same program in depian linux with valgrind. Valgrind didn't find any errors. I didn't find a way how to compile valgrind to that embedded linux. Is it possible that valgrind doesn't find all the error from threads? Can you help me somehow?