That depends, if your country is a war profiteering nation like US, UK and Germany then you're likely going to see an increase in your national GDP but if your country is the warzone, it's probably a likely thing that your GDP won't be that huge.
That depends, say for example in a war torn country that has the largest factory of a particular company and the factory of that company was a casualty to the war, I think that could be a case that the stock price of that particular company or if they've got a really big customer/consumer base in a war torn country then probably we would see the same thing too but if they don't have those, I don't think war affects a stock price that much.