Hi,
You should be using six 12V batteries ---- 3 to generate +36V and other 3 to generate -36V (not 34V). Centre point of 6 batteries which are connected in series is the ground point, with respect to which you measure +36V and -36V. Connect this ground with PCB ground.
If you are using lead-acid battery, voltage can go as high as 13.8V under fully charged condition. That means maximum terminal voltage can rise upto +/-41.4V. Make sure that the IC can withstand this supply.