I’ve been trying to set up a new Stock Image (replacement for ZD&T) and had many problems.
One of the problems I had was I could only get screen size of 80 columns and 24 rows, despite configuring everything I could think of to be larger.
The solution
Background
3270 Screens used to be 80 characters wide, with 24 lines. (Going back to the start they were 80 wide, 12 lines deep!) Then there were 3278 model 5’s which were 132 characters wide, 27 lines deep. Skipping a few decades, you can get 3270 emulators which you can configure to have what ever size you want. For example 160 characters wide and 60 lines deep. For these you either need very good eyesight, or a very large scre…
I’ve been trying to set up a new Stock Image (replacement for ZD&T) and had many problems.
One of the problems I had was I could only get screen size of 80 columns and 24 rows, despite configuring everything I could think of to be larger.
The solution
Background
3270 Screens used to be 80 characters wide, with 24 lines. (Going back to the start they were 80 wide, 12 lines deep!) Then there were 3278 model 5’s which were 132 characters wide, 27 lines deep. Skipping a few decades, you can get 3270 emulators which you can configure to have what ever size you want. For example 160 characters wide and 60 lines deep. For these you either need very good eyesight, or a very large screen.
I typically work with 132 wide, 43 lines deep.
With early 3270’s you had to configure the host system with the characteristics of the terminal, for example giving the screen size (80 * 24) it has an alternate screens (132 * 43), and what character sets etc it used.
Later models had a “query” capability. When queried, the 3270 can return its characteristics. This made configuring the host much easier, because you just defined it as query-able.
Configuring MVS
You have to define each locally attached device to MVS. For example address 0700 to 0720 are 3270s’.
Then you had to defined the devices to VTAM (this was the days before TCPIP).
For example
LOCAL700 LBUILD ****** LOCAL NON-SNA TERMINALS 701-71F **** * L700 LOCAL CUADDR=700, DLOGMOD=DYNAMICB, MODETAB=OLDINCLM, TERM=3277, ISTATUS=ACTIVE, USSTAB=USSTABVS L701 LOCAL TERM=3277,DLOGMOD=NSX32702, CUADDR=701,USSTAB=USSTAB, ISTATUS=ACTIVE, FEATUR2=(MODEL2)
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For device L700,
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this is a TERM=3277 on ControlUnitAddress=0700.
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When you make it active it displays a Welcome screen called USSTAB=USSTABVS
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The define characteristics are defined in a table (the MODETAB=OLDINCLM) with label DLOGMOD=DYNAMICB.
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For device L701
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this is a TERM=3277 on ControlUnitAddress=0701.
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When you make it active it displays a Welcome screen called USSTAB=USSTAB
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The define characteristics are defined in a table (it defaults of MODETAB=ISTINCLM) with label DLOGMOD=NSX32702
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The default logmode table ISTINCLM is here. You create it with Assembler macros.
The entry for NSX32702 has
*********************************************************************** LOGMODE TABLE ENTRY FOR NON-SNA 3270 DEVICES WITH ** EXTENDED DATA STREAMS (3278 OR 3279). ** SCREEN SIZE IS 24 X 80. ***********************************************************************NSX32702 MODEENT LOGMODE=NSX32702,FMPROF=X'02',TSPROF=X'02', * PRIPROT=X'71',SECPROT=X'40',COMPROT=X'2000', * RUSIZES=X'0000', * PSERVIC=X'008000000000185000007E00', * APPNCOS=#CONNECT
A screen using this has just s 24 * 80 screen size.
The next entry has
TITLE 'NSX32703'*********************************************************************** LOGMODE TABLE ENTRY FOR NON-SNA 3270 DEVICES WITH ** EXTENDED DATA STREAMS (3278 OR 3279). ** PRIMARY SCREEN 24 X 80 ** ALTERNATE SCREEN 32 X 80 ***********************************************************************....
so you could use this one to get 24 or 32 lines deep.
The definition for D4A32XX3 says
PRIMARY SCREEN 24 X 80 (1920) ALTERNATE SCREEN TO BE DETERMINED BY APPLICATION
I could not get this to work.
Linux definition
I created my Linux 3270 session using
x3270 -model 5 tso70@localhost:3270 &
Where the model 5 is 132 wide, 43 deep.
When I used the DLOGMOD=DYNAMICB, I logged on OK.
Configure ISPF
In ISPF, using the SETTINGS command. Scroll down to Terminal settings.
I did this and got a big screen.
At the top of the screen is
Select Environ, 1. Environ settings, Terminal status 2, Query terminal information.
Mine gave
Change the VTAM setup
In ADCD.Z31B.VTAM.SOURCE(ISTINCLM) on my old zD&T system, it defines
MODEENT LOGMODE=DYNAMICB,
I copied the load module ADCD.Z31B.VTAMLIB(ISTINCLM) to SYS1.VTAMLIB(OLDINCLM)
I defined the terminal definition SYS1.VTAMLST(LOC700) to have
LOCAL700 LBUILD L700 LOCAL CUADDR=700, * DLOGMOD=DYNAMICB, * MODETAB=OLDINCLM, * TERM=3277, X ISTATUS=ACTIVE, X USSTAB=USSTABVS
and activated it
v net,act,id=loc700
Published December 25, 2025