How can i change a gameobject scale to only one direction ?

 void Update()
     {
         if (DetectPlayer.touched == true)
         {
             if (raiseAmount < raiseTotal) 
             {
                 float raiseThisFrame = speed * Time.deltaTime; 
                 if (raiseAmount + raiseThisFrame > raiseTotal)
                 {
                     raiseThisFrame = raiseTotal - raiseAmount;
                 }
 
                 raiseAmount += raiseThisFrame;
 
                 gameObjectToRaise.transform.localScale += new Vector3(raiseThisFrame, raiseThisFrame, 0);
                 cubes[0].transform.localScale += new Vector3(raiseThisFrame, raiseThisFrame, 0);
                 cubes[0].transform.position += Vector3.left * (speed / 2) * Time.deltaTime;
             }
             else
             {
                 raised = true;
             }
         }
     }

When i'm changing the cube[0] scale it will change it to front and to back. But i want it to scale it only to the front direction. I mean to scale the axis x but not to stretch it like back and front only to the front.