my quick test says there are two chars, CR and LF, on an AIX and on Ubuntu

USER>s str=##class(%GlobalCharacterStream).%New()
USER>d str.WriteLine("Test")
USER>d str.Rewind()
USER>zzdump str.Read(100)
0000: 54 65 73 74 0D 0A                                       Test..
USER>
​USER>w $zv
Cache for UNIX (IBM AIX for System Power System-64) 2017.1 (Build 792U) Mon Mar 20 2017 19:19:37 EDT
USER>

-----------------

USER>s str=##class(%GlobalCharacterStream).%New()
USER>d str.WriteLine("Test")
USER>d str.Rewind()
USER>zzdump str.Read(100)
0000: 54 65 73 74 0D 0A                                       Test..
USER>
​USER>w $zv
Cache for UNIX (Ubuntu Server LTS for x86-64) 2017.1 (Build 792U) Mon Mar 20 2017 19:22:31 EDT
USER>

Maybe, your problem has nothing to do with Cache?

Regards,

Julius