code: public Clob createNewClob(int blockSize) throws PersistException {
          StoredLob lob = mLobStorage.prepare();
          lob.setLocator(mLocatorSequence.nextLongValue());
          lob.setBlockSize(blockSize);
          lob.setLength(0);
          lob.insert();
          return new ClobImpl(lob.getLocator());
      }
docs: Returns a new Clob whose length is zero.
  
  @param blockSize block size (in <i>bytes</i>) to use
  @return new empty Clob