copy-file: why this value for IO_SIZE

[Křištof Želechovski]

<URL: 
http://git.savannah.gnu.org/gitweb/?p=gnulib.git;a=blob_plain;f=lib/copy-
file.c >

has IO_SIZE = 32 * 1024

This number is used to specify the buffer length for copying data from one 
file to another, something that neither ANSI C nor POSIX directly supports.  
It is not configurable.  How was that number obtained?  Is it because it is 
half of memory segment?  But then, doesn’t it fail to allocate in 16-bit 
applications that use most of their memory?  And is it the best choice for a 
32-bit architecture too?  I ask because I am looking for a good buffer size 
for an application that copies data between files.

Chris