In the params.dat file, you can set it so the blockchain continues to write new blocks even if there are no transactions, this way there is a block for every interval since the creation of the genesis block. If you have a public chain, this is what helps keep it alive when there are no users (transactions), because miners continue mining/securing it. For private blockchain, if there is no native coin or no mining reward, there there is no need to continuously mine... but of course you can setup your blockchain to do so -whatever your reason.
