Since this will be a LIFO (Last In First Out) I have came up with the following. If anyone could suggest any improvements then they are most welcome.
Code:
'CSEH: Skip
Option Explicit

Public colStacks() As String

'LAST IN FIRST OUT!

Public Sub PushStack(ByVal strProcedure As String)
    'when in error handling routine then don't register traces
    If SkipTrace = True Then Exit Sub

    If ArrayInit(Not colStacks) = False Then
        'initialized
        ReDim Preserve colStacks(0)
        colStacks(0) = strProcedure
    Else
        'increase size
        ReDim Preserve colStacks(UBound(colStacks) + 1)
        colStacks(UBound(colStacks)) = strProcedure
    End If
End Sub

Public Sub PopStack()
    If SkipTrace = True Then Exit Sub

    If ArrayInit(Not colStacks) = True Then
        If UBound(colStacks) = LBound(colStacks) Then
            Erase colStacks
        Else
            ReDim Preserve colStacks(UBound(colStacks) - 1)
        End If
    End If
End Sub

Public Function GetTraces() As String
    Dim strMessage  As String
    Dim a           As Long
    Dim b           As Long

    If ArrayInit(Not colStacks) = True Then
        'add the callers
        b = UBound(colStacks)
        For a = LBound(colStacks) To UBound(colStacks)
            If a = 0 Then
                strMessage = strMessage & ("[Stack " & Format$(b, "00000") & " of " & Format$(UBound(colStacks), "00000") & "] " & colStacks(a)) & vbNewLine
            Else
                strMessage = strMessage & ("                   [Stack " & Format$(b, "00000") & " of " & Format$(UBound(colStacks), "00000") & "] " & colStacks(a) & " was called by " & colStacks(a - 1)) & vbNewLine
            End If
            b = b - 1
        Next
    End If
    If Len(strMessage) > 0 Then
        GetTraces = Mid$(strMessage, 1, Len(strMessage) - 2)
    Else
        GetTraces = strMessage
    End If
End Function

' usage: If ArrayInit(Not ArrayName) Then ...
Public Function ArrayInit(ByVal Not_Array As Long) As Boolean
    ArrayInit = Not (Not_Array = -1&)
    Debug.Assert App.hInstance
End Function