$ifRCWAzgbsv is the command to solve inverse matrix by using zgbsv solver.
The memory use is equal to (18Nf+3)*N*8 (bytes) ( N = (2*(2Nf+1)*Nlayer) )
The $ifRCWAzgbsv setting in GUI interface is here
1. Press RCWA and check the box for Use zgbsv as needed!