SNAX/HLS Configuration and Control Manual

Step 2. Planning SNAX Requirements
Planning the SNAX/HLS Environment
2–4 104705 Tandem Computers Incorporated
Special Device Data Streams
Implementing an emulation of a 327x display device is a major effort. It is therefore
recommended that communication with such a session partner employ data records
without screen control fields. The partner can process such data using unformatted
operations (that is, no BMS map under CICS or null MFS under IMS).
Use of Function Management Headers (FMHs)
You should be careful to define the control regions of the IBM application system to
reflect FMHs. For example, if a CICS application sends a message to a SNAX/HLS
application and the application has been described to CICS as a 3600, CICS overwrites
the first three bytes of the application data unless the CICS application specifies FMH
in the SEND command and uses nonstandard FHM notation. For further information,
see FMH under “Device-Support Planning” earlier in this section.
Special SNA Requests
Typically, IBM application programs have no control over special SNA requests or
responses. IBM control regions, however, use special requests or responses for
managing message exchange. It is common to find such requirements in advanced
BMS (CICS) or MFS (IMS) applications. If data records (not screens) are used, this
should present no problem. If a special request is required, however, you might need
customization routines to implement it. (See the SNAX/HLS Application Programming
Manual.)
Device SNA Protocol Requirements
You need to be aware that some IBM application systems are not BIND-driven. For
example, CICS does not respect the BIND delivered in the CINIT message from
VTAM. Rather, CICS uses SNA protocols derived from internal tables (mainly the
TCT) and from macro modifiers on function calls (for example, FMH). To avoid
problems, add appropriate entries into the VTAM LOGMODE table specifying BINDs
that follow SNA protocol and are therefore acceptable to SNAX/HLS. In particular,
specify the correct send/receive mode, the use of brackets, and the sequence number
verification attribute.
Step 2. Planning
SNAX/XF
Requirements
This subsection discusses the consistent configuration of SNAX/XF and VTAM/NCP
SDLC links. It is important that these links be planned and tested early so that testing
of applications can be relatively simple.
Note The information in this subsection is specific to SNAX/XF. For specific planning requirements for
SNAX/CDF, refer to the SNAX/XF and SNAX/CDF Device-Access Methods Programming Manual.