Boost multi-index based orderbook
myDecimal is an absolutely unhelpful name overall.  I don't see any need to give int64_t a typedef here, but even if there is one, then it should still use a better name.
Empty void parameters are not needed in C++:


OrderBook(void);
~OrderBook(void);



You also don't need these defaults as the compiler will provide them for you.  They would only be necessary if you need to overload them and will still need default versions.
It's a little less-readable not having whitespace after commas:


BOOST_MULTI_INDEX_MEMBER(OrderBookItem,myDecimal,price)



Not only that, but you already add this whitespace in other places.  Keep it consistent.

BOOST_MULTI_INDEX_MEMBER(OrderBookItem, myDecimal, price)

You use different styles of curly braces.  C++ doesn't restrict you to a particular one, so choose one you prefer and stick with it.
Although this line has been commented out, are you still using C++11?


// auto curLevel = buyContainer.get&lt;name&gt;(price);



If so, then you can replace OrderBookContainer::iterator with auto:

auto it = buyContainer.insert(price_).first;




auto it = sellContainer.insert(price_).first;