On PPC, functions used as Callback have got no stack. So they must not contain local variables.
A warning message shall be displayed at compile if a function with name prefix "Callback" has local variables.
the problem is not special for PPC. So, if a POU, registered as callback via taskconfiguration, contains local variables, a warning is produced.
To handle the situation when a callback is used with SysCallbackRegister, we produce also a warning for all functions with local variables starting with "callback" on PowerPC-systems. So sometimes the warning may be produced twice.