Hello Jaeyong,
Also, is there a particular reason that you position thread_base in between stack and stack base? If not, I think placing stack and stack_base right next to each other would be better (just an opinion).
there is no particular reason for this sequence. It is important that 'stack' is the first member but we could make 'stack_base' the second one if this makes the code easier to swallow.
Best regards Norman