View source for Access OS/390 3270 display sessions from OS/400 over SNA/APPN

This is a short writeup of how to configure access to '''OS/390 3270 display sessions from OS/400 over SNA/APPN'''. A mandatory requirement is an already working SNA/APPN configuration between the two machines.

This article assumes OS/390 ADCD 2.10 being used.

<blockquote>'''Note:''' The configuration is somewhat complex, and this article is mainly a writeup to the point of apparently complete configuration. The desired functionality unfortunately does '''not''' work as expected: Logon is not possible.</blockquote>

== Setting up VTAM ==
3270 display LUs are by nature dependent on a central PU to bring them up and down. This is a reminiscence of subarea (hierarchical) SNA. For that reason, VTAM must provide DLUS (Dependent LU Server) services.

Create a new member ''SYS1.LOCAL.VTAMLST(ASDLUS)'':
 ASDLMJ  VBUILD TYPE=SWNET
 *
 O390DLPU PU    IDBLK=056,
                IDNUM=03270,
                ISTATUS=ACTIVE,
                MODETAB=ISTINCLM,
                NETID=APPN,
                SSCPFM=USSSCS
 *
 O390DS02 LU    LOCADDR=02,
                DLOGMOD=SNX32702,USSTAB=USSS
 O390DS03 LU    LOCADDR=03,
                DLOGMOD=SNX32702,USSTAB=USSS
 O390DS04 LU    LOCADDR=04,
                DLOGMOD=SNX32702,USSTAB=USSS

Vary on this major node definition ''ASDLUS'' via console.

== Setting up OS/400 ==
* Create the Display Devices:
 crtdevhost devd(o390ds02) locadr(02) rmtlocname(o390ds02) ctl(o390dl) apptype(*eml)
 crtdevhost devd(o390ds03) locadr(03) rmtlocname(o390ds03) ctl(o390dl) apptype(*eml)
 crtdevhost devd(o390ds04) locadr(04) rmtlocname(o390ds04) ctl(o390dl) apptype(*eml)
* Create the Controller Description referencing the Display Devices:
 crtctlhost ctld(o390dl) linktype(*dlur) switched(*yes) appn(*yes) dev(o390ds02 o390ds03 o390ds04) sscpid(050000000059) lclexchid(05603270) swtdsc(*no) msgq(*sysval) pridlus(o390 *netatr) deppuname(o390dlpu)

<blockquote>'''Note:''' The SSCPID from my VTAM is 59, but ''crtctlhost'' wants a 05 in front. On the other hand, when setting it to the same value, VTAM complains <tt>IST1054I VALUE FOR SSCPID MUST BE BETWEEN 0 AND 65535</tt>. Not sure what to do about this. Maybe the 05 is kind of a flag?</blockquote>

Vary on the DLUR controller:
 vrycfg cfgobj(o390dl) cfgtype(*ctl) status(*on)

While there is no indication on the OS/390 console, you should get messages message in the ''qsysopr'' message queue that a CP-SVR-Pipe  is now active.

== Matching parameters ==
{|class="wikitable"
!VTAM Parameter
!OS/400 Parameter
!Comment
|-
|idblk/idnum
|lclexchid
|
|-
|locaddr
|locadr
|
|-
|os390dlpu
|ctld, deppuname, ctl
|Switched node PU name
|-
|o390ds02
|devd, rmtlocname
|Keep names equal, use 02 as template for more LUs
|-
|sscpname
|pridlus
|Take from VTAM config ''ATCSTRxx''
|}

== Testing ==
The ''streml3270'' command can be started with either a specific controller description, a device description, or a location name. For our testing, we can safely assume all LUs on OS/390 are currently free for use.
 streml3270 emldev(o390ds02)

You can enjoy a setup screen akin to ''strpasthr''. Afterwards, the screen shows a logon greeting.

== Weblinks ==
* [https://github.com/SDL-Hercules-390/hyperion/blob/master/readme/README.SNA.md Hercules SNA support README], GitHub
* [https://www.ibm.com/resources/publications/OutputPubsDetails?PubID=SC41540602 AS/400 Communications Management], SC41-5406-02
* [https://www.ibm.com/resources/publications/OutputPubsDetails?PubID=SG24620400 S/390 Partners in Development: OS/390 (and z/OS) New Users Cookbook], SG24-6204-00
*[https://www.ibm.com/support/pages/dlur-overview-and-configuration DLUR Overview and Configuration], ibm.com

[[Category: Software Configuration Guide]]‏
[[Category: System Administration‏‎]]