C++11: does atomic::compare_exchange_weak support none-primitive types?

I've got the following code:

#include<atomic>
#include<iostream>
using namespace std;

struct Big{
    int i;
    int j;
    int k[100];
};
int main(){
    atomic<int> i;
    cout<<i.load()<<endl;
    i.store(20);
    cout<<i.load()<<endl;
    i.exchange(30);
    cout<<i.load()<<endl;

    atomic<Big> ab,expect,value;
    ab.compare_exchange_weak(expect,value,memory_order_release,memory_order_relaxed);//error
    return 0;
}

Well, atomic works well, but I wish to see if none-lock function of compare_exchange_weak could work for complex data structures. Compiled with --std=c++11 it gives me:

error: no matching member function for call to 'compare_exchange_weak'
    ab.compare_exchange_weak(expect,value,memory_order_release,memory_order_relaxed);
    ~~~^~~~~~~~~~~~~~~~~~~~~
candidate function not viable: no known conversion from 'atomic<Big>' to 'Big &' for 1st argument
    bool compare_exchange_weak(_Tp& __e, _Tp __d,

So my question:

1. Does std::atomic::compare_exchange_weak work with complex structures?

2. If intel cpu hardware CMPEXG only works within 64 bit length cache line, does structures larger than 8 bytes work with CMPEXG? Is it still atomic operation?

3. How to fix my program?

Thanks.