Option Explicit
 
Dim Stack(255) As String
Public StackSize As Byte
 
Public Sub ClearStack()
    StackSize = 0
End Sub
 
Public Function Peek() As String
    Peek = Stack(StackSize)
End Function
 
Public Function Pop() As String
Dim Buffer As String
    Buffer = Stack(StackSize)
    StackSize = StackSize - 1
    Pop = Buffer
End Function
 
Public Sub Push(ByVal Expression As String)
    StackSize = StackSize + 1
    Stack(StackSize) = Expression
End Sub

Wissen ist Macht nichts wissen macht auch nichts