Reserve allocation is the value in which you wish to hold back for Manual/Auto DCA. This will not be touched by your bot until your Auto DCA threshold and strategy conditions are met or you place a manual DCA order.
This setting can be found under the Settings Tab in your bot
In the Summary section just above your open positions in the Positions Tab, you will see Reserve this shows how much of your reserve you have currently utilised laid out as
Amount used / Maximum Value (user defined)