And no one, not even China has a fiscal reserve -- every major government has deficit and relies on debt financing. So in its place, central bank increase liquidity by actions such as printing money (e.g. qualitative easing), decrease bank reserve requirement, and decrease interest rate. The reason central banks do not like to do those is because they have bad consequences and are hard to withdraw/reverse.

Since economy isn't doing well, it is deflationary or on the verge of it. So to counter it, you need something inflationary to counter -- government spending more and/or bank loosen liquidity. If you actually spend foreign reserve (buying foreign goods), it is deflationary because it increase the supply of goods. This is why countries in recession are tempted to adopt protectionist trade policies.