RTOS memory problem

Question

In Rtos holding 10kbytes of memory and your program for  asking for 5 kbytes and you got null error? Why does it take action like this?

Answer 1

RTOS might be holding 10k memory, might not problem of fragmentation, and the largest hole obtainable to user might be lesser than 5k, this condition might be one of the cause for NULL error.