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Boost.Coroutine2 provides the class protected_fixedsize_stack which models the stack-allocator concept. It appends a guard page at the end of each stack to protect against exceeding the stack. If the guard page is accessed (read or write operation) a segmentation fault/access violation is generated by the operating system.
| ![[Important]](../../../../../../doc/src/images/important.png) | Important | 
|---|---|
| Using protected_fixedsize_stack is expensive. That is, launching a new coroutine with a new stack is expensive; the allocated stack is just as efficient to use as any other stack. | 
| ![[Note]](../../../../../../doc/src/images/note.png) | Note | 
|---|---|
| 
          The appended  | 
#include <boost/coroutine2/protected_fixedsize.hpp> struct protected_fixedsize { protected_fixesize(std::size_t size = traits_type::default_size()); stack_context allocate(); void deallocate( stack_context &); }
stack_context allocate()
      
              traits_type::minimum:size()
              <= size
              and ! traits_type::is_unbounded() &&
              ( traits_type::maximum:size() >= size).
            
              Allocates memory of at least size
              bytes and stores a pointer to the stack and its actual size in sctx. Depending on the architecture
              (the stack grows downwards/upwards) the stored address is the highest/lowest
              address of the stack.
            
void deallocate( stack_context
        & sctx)
      
              sctx.sp is valid, traits_type::minimum:size() <= sctx.size and !
              traits_type::is_unbounded()
              && (
              traits_type::maximum:size()
              >= sctx.size).
            
Deallocates the stack space.