Can you do SFTP from a batch program without invoking the environments QP2TERM or...

QSH?
 
I need to build a program on the i5 in REXX or C to automate the
sending of files via SFTP or some secure method native on the i5 but
also native to a UNIX environment.   Again, all this without using any
QSHELL or other "called" environment.   Yes, QP2TERM and SFTP work but I
don't find any way to use SFTP in a batch i5 environment.    
 
As some background...The UNIX site I need to send files to asked me to
use SSL.  I thought great... that exists in the i5 FTP command.  But, no
go.  The best I could get is logged on to their site and thrown into
Passive Mode.  That's as far as I could go; not even LS worked.  Their
site just seemed to hang at that point.   Even trying to force to Active
mode didn't work. This after trying to get certificates to match,
exchange of public keys, etc.   
 
I need a way to do batch file transfers via a secure means directly
from the i5 to a UNIX environment using something commonly found in both
environments. 
 
Thanks in advance,
 
Dave