The following functions are supported only when VT AM Version 2 Release 2 operates with NCP Version 3:
• SNA network interconnection
• Channel-attachment NCPs
• Enhanced configuration and session awareness for data for NLDM Release 2
• Forced deactivation of an NCP link.
The following functions are supported only when VTAM Version 2 Release 2 operates with an NCP Version 2 or 3 for the 3725:
• CSP and MOSS dumps
• SIT trace.
VTAM Version 2 Release 2 operates with NCP Version 3, NCP Version 2, and NCP Version 1 Release 3.
Some of the functions of VTAM Version 2 require the appropriate release of NCP, as indicated in the previous section of this chapter.
VT AM Version 2 Release 2 supports only record-mode sessions. The Network Terminal Option program product (or a similar user-written program) can be used to support selected non-SNA devices in record-mode sessions.
VTAM Application Programs
As each new release of VT AM was developed, new application program facilities were added, obsolete facilities were deleted, and errors were corrected. Internal changes were also made to improve performance, reliability, availability, and serviceability. In this activity, the goal was to allow application programs that ran on a prior release of VT AM or on VTAM Level 2 to run on the new release of VT AM without modification or reassembly of the application program. However, in certain cases an application program must be modified.
The table in Figure 3-1 lists the factors to consider when moving an application program from a prior release of VT AM or VT AM Level 2 to VT AM Version 2 Release 2. Each factor is discussed in detail in VT AM Programming.
You may want to change a current program if it depends on the way a particular release of VT AM or VTAM Level 2 operates, such as the sequence of steps when processing an operator command or synchronous SIMLOGON macro instruction. You might also like to change a program to make use of the VT AM's networking capabilities.
When Migrating to VTAM Version 2 Release 2 From: 1 VTAME
or VTAM VTAM VTAM
Programming Factors To Be Version 1 Version 1 Version 2
Considered: Release 2 Release 3 Release 1
Sequence Number Dependencies for
X X
LU Type 0 3270 Terminals Logon Mode Names for Non-SNA 3270 Terminals
Search of Default Logon Mode Table Bracket Protocols for Non-SNA 3270 Terminals
Reporting Segmenting Errors Removal of Basic-Mode Support LOSTERM Exit Reason Codes
Reporting Failures When NIB USERFLD IS Specified
Parallel Sessions and the Use of NIBCID CLEAR Not Sent Before UNBIND SETLOGON OPTCD
=
QUIESCE SIMLOGON OPTCD=
CONALLCOS Name and Logon Mode Name X
Increase of ACB Size X X
Application Program Minor Node Name
X X
in BIND
1 You should also consider functions in this table that are available in the release of VT AM you are migrating from and you are intending to use for the first time with Version 2 Release 2. For exampl~, you might be migrating your system from VT AM Version 1 Release 2 and also adding parallel session capability to a current application program.
Figure 3-1. Factors for Moving Programs from Prior Releases of VTAM or VTAM Level 2
Programmed operator application programs can run unchanged, provided they do not depend on the structure or content of the VT AM message table ISTCFCMM. That is, no change is required for a programmed operator if it depends only on the documented programmed operator interface and on the content, structure, and meaning of the messages received through this interface. However, any programmed operator that depends on the structure or content of ISTCFCMM might need changes.
BTAM Application Programs
Existing application programs that use BT AM macros directly must be rewritten to operate with VTAM Version 2 Release 2. BTAM application programs that use an IBM application subsystem such as CICS/VS or IMS should require few changes, if any, to run on VTAM Version 2 Release 2.
Considerations for converting from BTAM to VTAM are discussed in Network Program Products Planning.
3-4 VTAM General Information
Related IBM Programs
If unformatted system services (USS) facilities are used to change VT AM messages, any NCCF customization code may need to be modified to ensure the correct routing of messages. Refer to Network Program Products Planning for more information. Related IBM programs such as CICS/VS, IMS/VS, POWER/VS, JESI/RES, JES2/RJE, TSO, VSPC, and SSS that are compatible with VTAM Level 2 or VTAM Version 1 are compatible with VT AM Version 2 Release 2 on the appropriate operating system release.
Recompilation of these programs is not required.
TCAM through VTAM is not provided with VTAM. However, TCAM can exist in the same host processor as VTAM.
Cross-Domain Communication
VT AM Version 2 Release 2 can support cross-domain communication for the following types of configurations:
• Multiple host processor configurations, operating with any combination of MVS or VSE operating systems, where each host processor has a network controlled by VTAM Version 2 Release 2 and NCP.
Optionally, some of the host processors may have networks controlled by the following currently supported access methods:
VTAM Version 1 Release 3 with its Multisystem Networking Facility or VTAM Version 2 Release 1, and NCP
TCAM Version 2 Release 3 or 4 with its Multisystem Networking Facility and NCP
VTAME.
• A network controlled by a single host processor with two access methods, VT AM Version 2 Release 2 and TCAM Version 2 Release 3 or 4 with its Multisystem Networking Facility, in conjunction with NCP.
• Combinations of the previous types of configurations.
In a multiple-domain network with both VTAM and TCAM, VTAM's access to device characteristics of the terminals controlled by TCAM is limited to those indicators defined and maintained by TCAM. In particular, VTAM cannot determine and, therefore, cannot provide to the application program the physical device address (used in the copy function) of an IBM 3271 Model 11 or 12 or any compatible device controlled by TeAM.
Two host processors can be attached through a channel-to-channel connection provided that both contain VT AM Version 2 and an OS/VS operating system.
In MVS only, the VTAM Encrypt/Decrypt Feature in one domain operates with a VTAM Encrypt/Decrypt Feature or TCAM Version 2 (or subsequent releases) in another domain to establish cross-domain cryptographic sessions. (Encryption/decryption is included in TCAM Version 2). The
Encrypt/Decrypt Feature does not operate with VT AM, TCAM, VT AME, nor with TCAM Version 1.
Initially, host processor locations that are to participate in a
multiple-domain network can install VTAM with single-domain networks, and the domains can be connected later with cross-domain links. This permits an existing domain to continue to operate while the
multiple-domain network is being developed. It should be noted that once a feature such as the optional Encrypt/Decrypt Feature has been installed, it is difficult to remove. Removing a feature requires regenerating the system and reapplying all of the features you wish to retain.
Cross-N etwork Communication
Conversion
VTAM Version 2 Release 2 can support cross-network communication, as long as the NCP with which it provides a gateway between networks is Version 3. It can also communicate with a VTAME. The configuration within each network can be any of those described above under
"Cross-Domain Communication" on page 3-5.
Cross-network encryption and decryption is available with the use of the Encrypt/Decrypt Feature at the gateway VTAMs, as well as at the hosts owning the session partners.
The complexity of the migration of a network to SNA network
interconnection depends on the configuration chosen and the methods of identifying cross-network resources. See the "Configuration Design" on page 1-14 for a short review of the factors involved.
VT AM Application Programs
User-written application programs that use the macro language and control block record-mode interface of VTAM Level 2, VTAM Version 1, or
VTAME will continue to operate on the same operating system with VTAM Version 2. This can be done witho~t changes (except those listed in
Figure 3-1) and without recompilation, provided that these programs do not depend on the internal processing characteristics of the access methods.
VT AM application programs generally will not need to be changed to operate with the Encrypt/Decrypt Feature. However, several SNA sense codes that deal with unrecoverable errors associated with the
Encrypt/Decrypt Feature have been introduced; existing application
programs may need to be changed to handle these codes properly. For more information about converting to VTAM Version 2 Release 2, see Network Program Products Planning and VT AM Programming.
3-6
VTAM General InformationBTAM Application Programs
User-written application programs that use BTAM macros directly must be rewritten to operate with VTAM Version 2 Release 2. You may redesign these programs to use an IBM application subsystem such as CICS/VS or IMS or recode them to use VTAM macros directly. For more information about designing application programs to use an IBM application subsystem, see the appropriate subsystem programming manual. For information about coding VTAM application programs, see VT AM Programming. For a comparison of VT AM and BTAM macro instructions, see Network Program Products Planning.
Converting BTAM application programs that already use an IBM
application subsystem should involve few changes in most cases. Refer to the appropriate subsystem programming manual for details.