FND_GLOBAL.APPS_INITIALIZE

Use below code to set the session.

fnd_global.APPS_INITIALIZE(user_id=>l_user_id,
                                                   resp_id=>l_resp_id,
                                                resp_appl_id=>l_resp_appl_id);

1. l_user_id is the fnd user ID which will be utilized during the call.
2. l_resp_id is the responsibility ID
3. l_resp_appl_id is the responsibility application ID.

Query to get the values.

select fnd.user_id , 
       fresp.responsibility_id, 
       fresp.application_id 
from   fnd_user fnd 
,      fnd_responsibility_tl fresp 
where  fnd.user_name = 'SYSADMIN' 
and    fresp.responsibility_name = 'RESP_NAME';