Secure File Transfer for Mainframe systems

[fereh]

Hi guys,
I would like to transfer files from UNIX machine to Mainframe system (using UNIX machine as client). The transfer process needs to be secure (i.e. data sent thro network should be encrypted using 128-bit encryption algorithm). I came to know that SFTP server is not available for Mainframe systems and hence using SFTP is not an option. Please let me know any other alternatives for the "Secured File Transfer to Mainframe system". Thanks!