Search notes:

oradebug dump systemstate

Dump systemstate with short callstacks (found in $ORACLE_HOME/rdmbs/admin/hangdiag.sql):

oradebug dump systemstate 267

MOS Note 4523581.1 asys about systemstate levels:

258	is a fast alternative but we'd lose some lock element data
267	can be used if additional buffer cache / lock element data is needed with an understanding of the cost

See also