Thanks LanX for the effort and answers! I am very grateful.

To understand something you need to create a conceptual model of it. I have realized that my model of Perl and the perl interpreter was not adequate.

By following your advice to deparse the generated code, I have start to understand what is going on. I have also read some introductions to the perl interpreter.

To know the use of the

Value Stack

This stack stores the values that regular perl code is operating on, usually intermediate values of expressions within a statement. The stack itself is formed of an array of SV pointers.

for the transfer of parameters to and return values from subroutines, helps me to build my model.