Tuxedo 8.1 tpreturn() does not release/free reply buffer.

I have tuxedo server in the LIVE environment and it is reporting very high
memory consumption.
I analysed the server to find any problem in the code which is causing any
memory leak in the server.
I found nothing which is wrong in the code.
Even I have taken help of purify which reported not any memory leak cases in
source code.
To simulate the case,I  developed a sample tuxedo service which is dynamically
creating certain MBs of fml buffer.It is then filling some data in the buffer
and retuens this buffer to the client.The size of reply buffer created by the
server is  defined by the client.
I was suprised to see,the consumptyion of memory  keeps increaseing  when client
are calling the service.
But these memory has not been released by Tuxedo when there is no  request from
client to the service.
Can any help me why tuxedo service does not release acquired memory when there
is  no request from a client.
The memory consumption of a tuxedo server keep on growing and remain as it is 
for very long time( 2 dyas+) even if there is no request from client during in
these days.