User Id from login screen

Guys,

I have a requirement wherein, the moment user logs into the logon screen for personas, he will be directed to a particular Z transaction....and that Z transaction will display list of Orders created by that User.

I was able to call the Z transaction by using the program : ADMIN_SET_START_TRANSACTION_FO

But to display the list of Orders created by the user id, I need to somehow capture the Id and then do a search in the table and display the results. How do I capture the User Id in this kind of scenario.

Any help would be highly appreciated.

Thanks,

Salil