A mast.Although it is attached to a mast the thing that holds a sail up is a halyard.
the pole that holds up the sail is called the mast
I believe you are referring to the shrouds and the stays that are attached to the mast(s) for stability. See the related link below:
A sail-robber? No, it's a MAST!
A halyard raises and lowers the sail. It is generally known as part of the boat's running rigging. The line that controls the mainsail's angle to the wind is called the mainsheet. The line that...