Addressing OLTP Solutions with CICS: The Transaction Server ... - Ibm

66 CICS for AIX as the Transaction Server
throughput, we recommend that you not run the cicsteld processes on the
same machine as the CICS for AIX region. The 3270 Telnet client consumes
much of the processor time on the client machine, so using a fast client
machine would improve the response time of the CICS transaction.
The 3270 Telnet client program, not cicsteld, provides the 3270 emulation.
You must ensure that the 3270 Telnet client program used provides the level
of data stream support, particularly the attributes settable by CICS basic
mapping support (BMS), required by your CICS transactions.
The cicsteld command authenticates to DCE with a DCE principal and
password from a keytab file when it is started up. The subsequent DCE RPC
call by the cicsteld is considered as an authenticated request when a 3270
Telnet client requests cicsteld to connect to the CICS for AIX region. The
3270 Telnet client is not asked to provide a password. The significance of
this is that access to CICS transactions and resources on your CICS for AIX
region is granted to any Telnet client user who is aware of the port that
cicsteld is listening on. There is a possible security exposure for your
transactions and resources if you choose an inappropriate DCE principal.
Our recommendations for creating a secure environment when using cicsteld
are:
− Restrict execution access to the cicsteld program to a controlled set of
users
− Set up cicsteld to run with the DCE principal associated with the CICS for
AIX region′s default userid that is the default for unauthenicated users
− Encourage Telnet clients to sign on to CICS by ensuring that cicsteld
invokes the CESN transaction as the first transaction.
For planning purposes, the storage requirements of the cicsteld process are
close to that of the cicsterm process. An instance of cicsteld must be started
for every connection between a 3270 Telnet client and a CICS for AIX region.
Therefore the number of running cicsteld processes reflects the number of
connections from the 3270 Telnet clients. The increased level of
authentication degrades performance.
4.5.5.2 Autoinstall User Exit
The CHAT transaction is responsible for performing an autoinstall of the WD for
the CICS Client for AIX, generating a terminal identifier based on the first two
characters of the client system. If you have your own version of the autoinstall
user exit in effect and the naming convention of the client system is to maintain
the same first two characters for all client systems, you may have to review its
logic to prevent possible duplication of terminal identifiers.
4.5.5.3 3270 Keyboard Mapping
The keyboard mapping for 3270 emulator operation is defined in a keyboard
mapping file. CICS for AIX provides a number of keymap files with a prefix name
of 3270keys in the usr/lpp/cics/etc directory for a variety of terminals such as
3151, hft, vt100, vt200, xterm, and sun-cmd. You may want to use the 3270 key
mappings provided with CICS instead of the defaults provided with the AIX
operating system. In this case, you have to link or copy the target keymap file to
the appropriate directory to make it effective. Alternatively you could make your
own copy of the keymap file. It is important to have the correct 3270 keyboard
mapping in place for each CICS end user. Otherwise user frustration due to the
wrong mapping of keys negates the benefits of using CICS Client for AIX