what am I doing wrong

I have a contoller script that my playerstats derives from. I want to put it on my main camera so that when you hit play the stats of each character here is what I am working with:

 using UnityEngine;
 using System.Collections;
 
 [RequireComponent(typeof(PlayerStats))]
 public class Controller : MonoBehaviour {
 
      public PlayerStats _jake;
 
    
 
    
 
    
 
     void Start(){
 
 
         _jake.level = 3;  
         _jake.STR = 50;
         _jake.DEX = 55;
         _jake.DEF = 50;
         _jake.vital = 100;
         _jake.Magic = 60;
         _jake.luck = 45;
         _jake.Speed = 56;
         _jake.Agility = 46;
         _jake.exp.Cur = 0;
         
     }
     
 }

note:Jake is just one of the characters that need this script there are four more party members too. here is PlayerStats:

 public class PlayerStats : Controller {
 
     public int level;
     public string name;
     public Stat Hp = new Stat();
     public Stat Mp = new Stat();
     
     
     public int STR;
     public int DEX;
     public int DEF;
     public int vital;
     public int Magic;
     public int luck;
     public int Speed;
     public int Agility;
     
     public int melee;
     public int ranged;
     public int MagA;
     public int MagD;
     public float active;
     
     public Stat exp = new Stat();
     
     public void addexp(int ex){
         
         exp.Cur += ex;
         while(exp.Cur >= exp.Max && level < 99){
             exp.Cur -= exp.Max;
             exp.Max = level *(level+1)* 500;
             level++;
             upstats();
         }
     
     }
     
     void upstats(){
         STR++;
         DEX++;
         DEF++;
         vital++;
         Magic++;
         luck++;
         Speed++;
         Agility++;
     
         
         melee =(level*7)+STR;
         ranged =(level*7)+DEX;
         DEF =(level*2)+ Agility;
         MagA =(level*7)+ Magic;
         MagD =(level*2)+ luck;
         
         active =20+((Speed * level)/1500);
         
         Hp.Max =((level * 5)+ vital)*10;
         Hp.Cur = Hp.Max;
         Mp.Max =((level * 5)+ Magic)*10;
         Mp.Cur = Mp.Max;
         
     }
     
         public class Stat{
         public int Cur;
         public int Max;
         
     }        
     
         public PlayerStats(int level,string name,int STR,int DEX,int DEF,int vital,int Magic,int luck,int speed,int Agility,int exp){
         this.level = 1;
         this.name = name;
         this.STR = STR;
         this.DEF = DEF;
         this.vital = vital;
         this.Magic = Magic;
         this.luck = luck;
         this.Speed = speed;
         this.Agility = Agility;
         addexp(exp);
     }    
     
 
 }

this script runs from the Project tab. and the controller script attaches to camera because it is for my characters all 5 of them who are in the party. I also am getting an error that says stack overflow extintion