What is the memory every node allocates locally for the Bitcoin blockchain?
Not all mining machines need to store the whole blockchain, as a miner you would normally have one or a few nodes which do that, and then just send a block template to all the actual mining machines (ASICs) to mine without caring about the blockchain. 

All non-pruned full nodes store the entire blockchain. It's possible to run in pruned mode which means older blocks are pruned and only the newest ones are kept, so you need less space, but this means those nodes can't serve old blocks to new full nodes trying to sync