code: private void initWriteBuffer()
                      throws IOException {
          if (headeroutbuf == null) {
              int buflen =
                              DWORDSIZE + // room for next
                                              SWORDSIZE + // room for hash
                                              DWORDSIZE + // room for old format: last update
                                                          //          new format: validator expiration time (VET)
                                              DWORDSIZE + // room for old format: last reference
                                                          //          new format: H-WORD - unused; L-WORD - hashcode for cache value
                                              DWORDSIZE + // room for first creation
                                              DWORDSIZE + // room for expiration (RET)
                                              DWORDSIZE + // room for old format: grace 
                                                          //          new format: magic, version & data size
                                              SWORDSIZE; // room for key size
  
              headeroutbuf = new byte[buflen];
              headeroutbytestream = new ByteArrayPlusOutputStream(headeroutbuf);
              headerout = new DataOutputStream(headeroutbytestream);
          }
          headeroutbytestream.reset();
      }
docs: ***********************************************************************
  This preps the the reusable output buffer for writing object heders to
  reduce the number of physical writes needed to write an object to disk.
  ***********************************************************************