all Studio settings are stored in Windows registry.
Search with regedit for InterSystem

If this user should also be programmer you can create a new role copying from %Developer
and then remove the DB's that you want him to lock out like this  just for NS = USER

.

For an engineer this sounds like a quite challenging exercise to rewrite a PGP lib in COS.
 

But it seems more promising to wrap the existing (and hopefully well tested) code and consume it from Caché using one of the existing Gateways:

- Callout Gateway http://docs.intersystems.com/latest/csp/docbook/DocBook.UI.Page.cls?KEY=...

- ActiveX Gateway  http://docs.intersystems.com/latest/csp/docbook/DocBook.UI.Page.cls?KEY=...

- or just  connect
over TCP/IP http://docs.intersystems.com/latest/csp/docbook/DocBook.UI.Page.cls?KEY=...
or UDP http://docs.intersystems.com/latest/csp/docbook/DocBook.UI.Page.cls?KEY=...
or a Pipe  http://docs.intersystems.com/latest/csp/docbook/DocBook.UI.Page.cls?KEY=...

I bet the community has even more ideas to reuse the existing code

indeed this is surprising.

but is this really:   do content.ReadLine(,,isEOL)

it should be a pass by reference to receive something back do content.ReadLine(,,.isEOL) 
with the <dot> in front of the variable 

You still have the option to create your own %ZLANGC00.int 
and make you own ZZEXIT to avoid the risky HALT

It's a miracle to me how HALT could survive from PDP-7 sn#103 at MGH and nobody touched it.

                           

to me this looks like your content had an extra $C(13,10) at the end.
It could help to  have the full content at hands. 
eg:
before  content.OutputToDevice()
set ck=content.Read()
set ^ck($i(^ck))=ck
do content.Rewind()

I expect  zwrite ^ck will show more than 3  lines
That would indicate that the source of trouble is on the input side. 
Some closing action ?   

if you change wnl() ...
to
wnl()  quit
you just disable it to see if it plays a role at all    

I don't see a call for  wnl()   
but ancient coding practices  would suggest its:  writenewline just that
and that's what it does without any other content.
though the remark is rater direct if interpreting feedback := line

// Should be smart as well: routines ending with write ! will create an empty feedback!

just a guess:
with do content.MoveTo(content.Size - 1)   you are probably just between CR and LF 

Could you try do content.MoveTo(content.Size - 3)  just to make sure you a e before CRLF

I'm not sure how EOL is triggered
eventually also check returned success code

1)  
%Stream.GlobalBinary has a warning:

Note that on a unicode Cache although you can write unicode data into this class and read it back out this is not a supported use of this class and the Size property would be incorrect in this case as it would be the size in characters rather than the size in bytes

2)
   do content.OutputToDevice()
now your content is out and you are positioned at end

    do content.MoveTo(content.Size)
now you re-read content until LastCharacter-1, whatever total size might be
    set isNewLineTerminator = (content.Read(1) = $char(10)) 
reading the assumed last character

3)
you might be better off to use  content.ReadLine(,.sc,.eol) and check eol for the termination status

The first thing to check in Mgmt Portal is size of Global Buffers  - Rule of thumb: 50% of available RAM
http://<yourhost>:<yourport>/csp/sys/mgr/%25CSP.UI.Portal.MemoryStartup.zen

Check Cache Efficiency in System Dashboard before and after restart
http://<yourhost>:<yourport>/csp/sys/op/UtilDashboard.csp?$NAMESPACE=

Thanks Ed! 
I just went through old DC post for half an hour+ to detect it. 

It's much better than my link to Facebook. 

Regards

do you look for this one?

%ENSInstallDir%\CSP\broker\portal\EnsembleLogo210x50.png