DB2 8.1 for LUW (Unix,etc) does not currently support ROWID (direct storage of the internal DB2 rowid). The closest thing would probably be:
CREATE TABLE XXXX
(IDCOL INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY
(START WITH 1, INCREMENT BY 1),
You can use certain other numeric data types in addition to integer. This column can be populated by the load/import command.
You might want to consult the following guide downloadable from the IBM website: "SQL Reference for Cross-Platform Development Version 1.1"