OS/2 and AS/400 are completely different operating systems.
Find the SQL Reference manual for your platform and look in the Appendix for Catalog Tables or Catalog Views. On some platforms (like mainframe) it would be called sysibm.systables with a "V" in the TYPE column.
On Linux, UNIX, and Windows (and older DB2 versions that supported OS/2) you can query syscat.tables with with a "V" in the TYPE column. or you can query sycat.views.