You will not be able to do that. The server.execute is different than a simple include. The code in the execute call runs in a different space than the caller. You cannot easily pass information from the caller to the called code. In particular, variables are not shared. An option explicit statement at the top of the called code will help make this more apparent. The str_text variable in the called file does not refer to the same str_text variable in the calling file.
You can pass information between between the two files with cookies, session variables, or, possibly the database. Any other approach is problematic.