Our margin rules:
Margin Call: 100%
Stop Out level: 70%
If you reach 100% you will get a margin call and you will not be able to open any trades.
If you reach 70% Margin or below, a Stop-Out will occur at which MetaTrader will start to close your open positions one by one.
To keep your margin levels high, you can either boost your equity by adding more margin to your account or reduce the margin you're trading on by reducing the lot size of your holdings.