Option Explicit
Private CancelFlag As Boolean
Private RunnningFlag As Boolean
Private Sub Command1_Click()
    Label1 = vbNullString
 
    If RunnningFlag Then
        CancelFlag = True
 
        While RunnningFlag
            DoEvents
        Wend
    End If
 
    Call Stacktest
End Sub
Private Sub Stacktest()
    Dim i As Long
 
    RunnningFlag = True
 
    For i = 0 To 100000
        Label1 = Str(Val(Label1) + 1)
 
        DoEvents
 
        If CancelFlag Then
            CancelFlag = False
            Exit For
        End If
    Next
 
    RunnningFlag = False
End Sub

While RunnningFlag
      DoEvents
Wend