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Stack allocation

Class stack_allocator
Helper functions

A fcontext_t requires a stack which will be allocated/deallocated by a StackAllocator. Boost.Context uses stack_allocator by default but a customized stack allocator can be passed to the context constructor instead. If a context is constructed it invokes allocate() function and by its destruction the stack gets released by deallocate().

StackAllocator concept

A StackAllocator must satisfy the StackAllocator concept requirements shown in the following table, in which a is an object of a StackAllocator type, p is a void *, and s is a std::size_t:


return type


a.allocate( s)

void *

returns a pointer to s bytes allocated from the stack

a.deallocate( p, s)


deallocates s bytes of memory beginning at p, a pointer previously returned by a.allocate()

[Important] Important

The implementation of allocate() might include logic to protect against exceeding the context's available stack size rather than leaving it as undefined behaviour.

[Important] Important

Calling deallocate() with a pointer not returned by allocate() results in undefined behaviour.

[Note] Note

The stack is not required to be aligned; alignment takes place inside make_fcontext().