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

From Try-AS/400
Revision as of 20:53, 8 May 2026 by PoC (talk | contribs) (→Testing: More detail)
Jump to navigation Jump to search

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.

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.

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    ADDR=02,
               DYNLU=YES,
               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)

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 IST1054I VALUE FOR SSCPID MUST BE BETWEEN 0 AND 65535. Not sure what to do about this. Maybe the 05 is kind of a flag?

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. 

Controller LRRRDL contacted on line *N.
CP-SVR pipe to DLUS POCNET.LRRR has been established.

Matching parameters

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.

Failure description

When trying to establish a Logon session to TSO, the following error message is written to the master console: 

20.37.18 STC00004  IST663I BIND FAIL REQUEST RECEIVED, SENSE=80040000
IST664I REAL  OLU=POCNET.O390DS02     REAL  DLU=POCNET.A06TSO02
IST889I SID = E7CB937FC08E0ADC
IST891I POCNET.NIBBLER GENERATED FAILURE NOTIFICATION
IST893I ORIGINAL FAILING REQUEST IS BIND
IST314I END
20.37.18 STC00029  IKT030I TCAS LOGON PROCESS FAILURE PLU=A06TSO02    SLU=POCNET.A06TSO02    SENSE= 80040000
20.37.18           IKT117I TSO/VTAM INITIALIZATION FAILED FOR APPLNAME=TSO0002 , LUNAME=POCNET.O390DS02
20.37.18           IKT111I APPLNAME=TSO0002  FAILED DUE TO: TCAS CLSDST PASS FAILURE
20.37.18           IKJ608I LOGON TERMINATED, IKTXINIT, TSO/VTAM INITIALIZATION ERROR
20.37.18 STC00004  IST804I CLOSE IN PROGRESS FOR TSO0002 OPENED BY ***NA***
20.37.18 STC00004  IST400I TERMINATION IN PROGRESS FOR APPLID TSO0002
20.37.18 STC00004  IST805I VTAM CLOSE COMPLETE FOR TSO0002

This happens likewise if the OS/400 is created with LUname A06TSO02.

Weblinks

Retrieved from "http://try-as400.pocnet.net/index.php?title=Access_OS/390_3270_display_sessions_from_OS/400_over_SNA/APPN&oldid=1714"