las3_pub / predictable_parallel_patterns

This requires the user to explicitly manage the storage duration/place of the thread local state, making a fine grained memory allocation simpler.

The local storage per thread is only a pointer, this must be assigned AFTER the local storage object has moved to it's final location (e.g. on the stack of the caller). We might even change this a little further in the future to make the location of the state object more transparent.