Option Explicit
Private class1() As class1
Private counter As Integer
 
Private Sub Command1_Click()
    If (Not Not class1) <> 0 Then 'Array dimensioniert?
        class1(0).cancel
        Set class1(0) = Nothing
        Erase class1
        ReDim class1(0)
        Set class1(0) = New class1
        class1(0).Stacktest
    Else
        ReDim class1(0)
        Set class1(0) = New class1
        class1(0).Stacktest
        Set class1(0) = Nothing
        Erase class1
    End If
 
    MsgBox "Durchlauf fertig"
End Sub

Option Explicit
Private cancelflag As Boolean
Private RunnningFlag As Boolean
Public Sub cancel()
    cancelflag = True
End Sub
 
Public Sub Stacktest()
    Dim i As Long
 
    RunnningFlag = True
 
    For i = 0 To 10000
        Form1.Label1 = Str(i)
 
        DoEvents
 
        If cancelflag Then
            cancelflag = False
            Exit For
        End If
    Next
 
    RunnningFlag = False
End Sub