도움이 되실런지 모르겠습니다. 저도 DB2에서 LOB 관련 자료를 찾다가 본 문서입니다.

http://www-106.ibm.com/developerworks/db2/library/techarticle/0310bhogal/0310bhogal.html

===== UPDATE ===============================================
String data = "111111111111111111111111111111111\n"
            + "222222222222222222222222222222222";
Reader reader = new StringReader(data);

sqlstr = " UPDATE TEST_TABLE        \n"
       + "    SET CLOB_FIELD = ?    \n"
       + "  WHERE PK         = '1'  \n"
       + "    AND SEQ        = '0'  \n" ;
      
pstmt = conection.prepareStatement(sqlstr);
pstmt.setCharacterStream(1, reader, data.length());
pstmt.executeUpdate();
============================================================

===== SELECT ===============================================
sqlstr = " SELECT CLOB_FIELD  \n"
       + "   FROM TEST_TABLE  \n"
       + "  WHERE PK = '1'    \n";
pstmt = connection.prepareStatement(sqlstr);
rs = pstmt.executeQuery();
if( rs.next() ) {
    Clob clob = rs.getClob(1);
    BufferedReader reader = new BufferedReader(clob.getCharacterStream());
    String line = null;
    StringBuffer text = new StringBuffer();
    while((line = reader.readLine()) != null)
        text.append(line).append("\r\n");
    return text.toString();
}
============================================================