If possible keep your wall 30 inches or less which I am almost certain is the cut off. Over 30 inches becomes an engineered retaining wall and quite expensive. If its 30 inches or less it is a sitting wall and does not need to be a permitted retaining wall. Of course, you will want to verify this for yourself but this is what I went through 12 years ago and why my wall is 30 inches high

MIne was a cinderbock wall wall covered in stucco to match my house and capped with the same flagstone that accents all my hardscaping both front and back. It has held up well and still looks very good.