autneticated message size restricted to 65535

[Alexander N. Moibenko]

Hello,
I recently found that authenticated message size (GSSAPI in my case) is 
restricted to 65535.
In cyrus-sasl there also is a restriction. According to gssapi.c it is 
0xFFFFFF=16777215.
In qpid SaslFactory.cpp it is hard-coded to secprops.maxbufsize = 65535; 
There are also some places where maxFrameSize is set to
65535. What does this mean? I know that there is a restriction on UDP 
message size, which is 64KB, but why there is a restriction to 
authenticated TCP/IP qpid message? There is not restriction to 
non-authenticated message though.
I wonder why it is set to such value and can anything else be done to 
safely increase this size not re-compiling the code?
Thanks,
Alexander.