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You can allocate stack space dynamically by using the C compiler’s malloc() function as shown in Listing 4.5. However, you must be careful with fragmentation. Specifically, if you create and delete tasks, your memory allocator may not be able to return a stack for your task(s) because the heap eventually becomes fragmented.
Because µC/OS-II supports processors with stacks that grow either from high to low memory or from low to high memory, you must know how the stack grows when you call either OSTaskCreate() or OSTaskCreateExt() because you need to pass the task’s top-of-stack to these functions. When OS_STK_GROWTH is set to 0 in OS_CPU.H , you need to pass the lowest memory location of the stack to the task create function as shown in Listing 4.6.
When OS_STK_GROWTH is set to 1 in OS_CPU.H, you need to pass the highest memory location of the stack to the task create function as shown in Listing 4.7.
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