Use these steps for the minimum information that you need
to start the TN3270E Telnet server. The steps refer to more specific
information about customizing your server.
Before you begin
You need to know how to create VTAM® definition
data sets; specifically, you need to know how to define VTAM application LUs. You need to set up and
know how to use a TN3270E client emulator. A maximum of eight Telnet
servers can be active at any time.
Procedure
Perform the following steps to start the TN3270E Telnet
server:
- Create a new data set member in your procedure library
for the TN3270E Telnet server JCL. A sample procedure
is in SEZAINST(EZBTNPRC). The only valid parameter that can be passed
in from the JCL (using the PARM= keyword on the EXEC JCL statement)
is the component trace options parmlib member name.
- Define security for a user ID and associate the user ID
with the Telnet procedure name; see Steps for defining security for a user ID and associating the user ID with the Telnet procedure name.
- Customize the VTAM configuration
data set to define VTAM application
LUs for Telnet to use; see Steps for customizing the VTAM configuration data set for Telnet.
- Customize the TCP/IP configuration data set. Reserve
your Telnet ports by using the PORT num tnproc statement
in the TCP/IP startup profile. If you do not code the PORT num tnproc statement,
another application might use the port before the Telnet application
can claim it.
- Customize the TN3270E Telnet server configuration data
set; see The TN3270E Telnet server configuration data set and Steps for customizing the TN3270E Telnet server configuration data set.
- Set the component trace options (CTRACE). Component
trace options are set in a separate parmlib data set member. The sample
procedure JCL points to a sample parmlib member, CTIEZBTN, in SYS1.PARMLIB,
which starts a minimum trace. Use this member unless you need to turn
on other options to debug a Telnet problem.
To change the component
trace options, specify a new parmlib member in the JCL. The member
has the form CTIEZBxx. For more information about
setting up trace options, see Telnet CTRACE.
- Set up the resolver input file. Use the default
search order unless there are special circumstances that require you
to use unique parameters. For example, if there are parameters that
are to be used only when the resolver is called by Telnet, you need
to define those unique parameters. Define the unique parameters in
a data set that is specified on the SYSTCPD DD statement in the Telnet
procedure JCL. For more information about resolvers and resolver configuration
files, see The resolver.
- Start Telnet by issuing START tnproc,
where tnproc is the Telnet procedure member
name.
Results
You should now see message EZZ6003I tnproc LISTENING
ON PORT nnnnn. To verify your configuration,
connect to the Telnet port from your Telnet client emulator; Telnet
uses the first Telnet LU that is available. A solicitor screen or
USSMSG10 screen prompts you to enter an application. Enter the name
of any valid SNA application to log on to that SNA application. If
an error occurs during session initiation, the MSG07 statement causes
an error message to be sent to the client. If you do not code the
MSG07 statement, then the connection is dropped.
Tips: - To help avoid any unnecessary IPL, specify REUSASID=YES on the
START command to ensure that the address space identifier (ASID) associated
with the Telnet address space can be reused. The Telnet address space
provides PC-entered services that must be accessible to all address
spaces, so a system linkage index (LX) is obtained. Unless you specify
REUSASID=YES on the START command, the ASID associated with the Telnet
address space will be nonreusable when the address space is stopped
or restarted. If the Telnet address space is stopped enough times
and REUSASID=YES is not specified when started, all available ASIDs
could be exhausted, preventing the creation of a new address space
on the system. In this case, an IPL is required. For more information
about tuning parameters for the maximum number of ASIDs on a system,
see the MAXUSER parameter in z/OS MVS Initialization and Tuning Reference.
- The default MVS™ program properties
table (PPT) entry sets Telnet to be a non-cancelable application.
As a non-cancelable application, a TCP/IP stack should not automatically
start Telnet using the AUTOLOG function. If the TCP/IP stack is recycled,
the stack tries to cancel and restart all AUTOLOG applications. A
non-cancelable application does not end and the following messages
are issued repeatedly:
N 0140000 SA6I 2005147 04:59:27.69 STC07087 00000084 EZZ0621I AUTOLOG FORCING IBMTNSI0, REASON: TCP/IP HAS BEEN RESTARTED
NR0000000 SA6I 2005147 04:59:27.71 STC07087 00000080 IEE838I IBMTNSI0 NON-CANCELABLE - ISSUE FORCE ARM
If
you want to set the priority for Telnet in the PPT, change the priorities
by assigning the job name to another service class in the STC subsystem.
The
default settings are: Privileged, non-swappable, non-cancelable, running
in key 6, and system task. With these settings, Telnet and the TCP/IP
stack have the same priority. The privileged or system task setting
causes the started job to be assigned to the SYSSTC service class.
- To change the IPv6 or INET environments, you must recycle the
Telnet procedure. Telnet checks for changes in the environment each
time a port is activated. If Telnet detects a change in the environment,
then the port is not activated. If you change from an IPv4 environment
to an IPv6 environment, from an IPv6 environment to an IPv4 environment,
from an INET environment to a CINET environment, or from a CINET environment
to an INET environment, then results are unpredictable on existing
ports.