Okay, So it is a common saying in the business world. CEO always need to have more shares. Share is the place that gives power to the CEO. At the start when you are writing a Memorandum of Association (Document required to register your company) you can write most terms in that document. But you have to follow some market norms, if you don't follow them, no one will invest in your company.
But market norms provide you protection. Always have a bigger share from all investors if you want to control your company.
Most business experts say the CEO should have 80%+ shares at the start. So when a new investor come and you give a few % shares to your investor, it will not impact your chunk majorly.