TeAM Programs Under VTAM
VTAM can coexist with QTAM and BTAM under DOS/VS and with BTAM and TCAM under OS/VS. QTAM programs, BT AM programs, and TCAM programs that do not use the communications controller in network control mode can be executed concurrently as long as they have separate telecommunication networks. Additionally, when VT AM and TCAM are both in the operating system, TCAM programs that use terminals attached to a communications controller in network control mode are supported through VT AM.
Figure 7-7 shows an OS/VS telecommunication system with TCAM and VTAM being executed concurrently.
TCAM application programs and the message control program (MCP) can share the resources of a VT AM telecommunication network with application programs written for VTAM. When sharing a network with TCAM, VTAM processes requests for all remote terminals attached to a communications controller in network control mode and, optionally, requests for locally attahced 3270s. TCAM supports terminals attached to other transmission control units, including those terminals attached to a communications controller in emulation mode (with or without PEP), and locally attached devices. The TCAM user can choose between having individual local 3270 devices supported directly or through VTAM.
Host CPU
TCAM
TCAM Programs
_ _ _ ... _ _ ... Transmission Control Unit (TCU) can be a TCU
2701, 2702, or 2703, or a communications controller in emulation mode
..
-VTAM Programs
,
VTAM
Communications Controller in Network Control Mode
VTAM and TeAM use VTAM to communicate with terminals in the VTAM network. TCAM programs, including TSO, can also communicate with terminals attached to a 2701, 2702, or 2703 transmission control unit, or through a communications controller in em~lation mode. The same communications controller can be shared by TCAM programs using emulation mode and VT AM programs using network control mode.
Figure 7-7. Communications Controllers and Transmission Control Units in a Telecommunication Network
TeAM Functions Not Available in a Shared Environment
The principal advantages of this shared capability are:
• The ability to share network resources between VT AM and TCAM programs
• The ability to allow terminals to log onto TCAM
• The availability of the queued-control capability of TCAM in a shared system
Existing TCAM application programs may not require changes, recompilation, or reassembly; their interface with the TCAM MCP remains the same. However, application programs that use TCAM operator control commands should be evaluated to ensure that they will operate as expected in the new environment.
The following TCAM macro instructions are altered for VTAM operation: CODE, INTRO, MSGFORM, MSGGEN, STARTMH, and TERMINAL. An MCP that uses any of these macro instructions must be reassembled.
TCAM in a shared VTAM and TCAM environment depends upon VTAM to exercise physical control over stations and lines attached to a communications controller in network control mode. Differences exist between OS/VS TCAM Release 5, which directly supports the communications controller in network control mode, and the version of TCAM that operates in a shared environment with VT AM. These differences consist of:
• TCAM functions not available in the shared VT AM and TCAM environment
• TCAM operator control functions that have an altered meaning in a shared VT AM and TCAM environment
• TCAM operator control functions that are replaced with similar VT AM functions available only from a system console
• TCAM operator awareness messages that are replaced with VTAM messages routed to a system console rather than to an operator control station or application program Certain functions supported by OS/VS TCAM Release 5 for the network control program are not available in the shared network. Some of these are partially replaced with VT AM functions, while others are not. The functions that are not available are listed below.
• Because VTAM restart after host failure requires a re-IPL and cold start of the NCP, the following items, which are checkpointed by TCAM Release 5 for warm start of the NCP after host failure, are not checkpointed in the VT AM/TCAM shared network.
TCAM's checkpoint/restart of its MCP is maintained as with TCAM Release S.
Line and terminal status Service seeking pause Session limit
Negative response limit Block-handler sets Transmission limit
Modifications to dial digits, polling characters, and addressing characters made as a result of ICHNG and TCHNG macros issued in TCAM application programs
For communications controller failure without host failure, VTAM provides warm start of the communications controller including items 1-6 listed above. The exception is item 7; that is, changes made by TCAM's ICHNG and TCHNG macros and the Modify BH Set operator command are not warm-started. These changes could be reestablished after the communications controller restart by a user-written TCAM application program which would maintain a record of changes and make the changes based on operator notification that the NCP has been restarted.
Chapter 7. VTAM Planning Considerations and Requirements 183
Altered TCAM Operator Control Functions
• The TCAM operator command to change the dial mode of a switched line between manual and automatic dial ("Change Dial Mode") for lines connected to a communications controller is not supported in the VTAM/TCAM shared system.
VT AM allows the user to specify the dial mode of a switched line during network generation.
• The TCAM operator command to set the NCP time and date ("Set 3705 Time and Date") is no longer supported. VT AM provides this function when the NCP is loaded.
• The TCAM operator command to display 32 contiguous bytes of communications controller storage ("Display 3705 Storage") is no longer supported.
• The TCAM Release 5 capability to designate a communications controller as a backup and then switch dynamically to this backup in the event of controller failure, using a warm start, is not provided for the VT AM/TCAM shared network. The operator commands involved ("Activate 3705 Backup," "Switch 3705 Backup," "Switch 3705s") are no longer supported. The VTAM user can manually switch between two communications controllers with appropriate physical switching equipment and use of VT AM's VARY command, but restart in the backup controller is cold.
• The TeAM Release 5 capability to dynamically switch a communications controller through a second Type 2 Channel Adapter to a backup CPU (with the "Switch 3705 Channel Adapter" operator command) is not supported in the VT AM/TCAM shared network. The VTAM user can start a new system in the backup CPU, and re-IPL the communications controller through the second Type 2 Channel Adapter. Operator-initiated switching through a second channel to the same CPU by a toggle switch on the communications controller is still available in the shared network; for more information on this feature see the OS/VS TCAM Programmer's Guide.
• The TeAM Release 5 operator commands for switching between specific and general polling for the 3270 Information Display System ("Activate General Poll," "Deacti-vate General Poll") are not supported for 3270 systems under the control of VT AM.
VT AM always uses general polling for these stations.
• The CUTOFF and MSGLIMIT message handler macro instructions are not applicable for stations managed by VT AM. The CUTOFF operand of the NCP's LINE macro instruction can be used.
• The "Read Full Buffer" support available in TCAM Release 5 for locally attached 3270 Information Display Systems is not available for locally attached 3270 stations managed by VT AM. Users who require this support, described in the
as/vs
TCAM Programmer's Guide, should use the IDS local support option available with TCAM.• The input data from a remote 3270 managed by VTAM does not contain the control unit or station addresses. The input format is the same for the local 3270 and remote 3270. (The output format is unchanged.)
Certain TCAM Release 5 operator command functions are modified in the VT AM/TCAM shared network environment. In the shared network, VT AM exercises physical control over the network, and certain TCAM functions which previously permitted dynamic physical reconfiguration are now limited to TCAM logical reconfiguration.
The operator commands involved are:
• Activate Station to Receive and Transmit
• Activate Station to Transmit
• Deactivate Station for Receive and Transmit
• Deactivate Station for Receive
• Start Line Transmission
• Stop Line Transmission
TeAM Operator Control Functions Replaced by VT AM Operator Control Functions
• Suspend Transmission
• Release Intercepted Station
The altered TCAM application program macro instructions are HOLD and MRELEASE.
For lines and stations associated with TCAM through VTAM, these commands and macro instructions are effective only for message traffic that is being handled by TCAM. If a line or terminal in the shared network is used only by TCAM, the operator command or macro instruction has the same effect as in TCAM Release 5. If, however, the resource is shared, data that is not handled by TCAM can still reach a station for which data flow has been inhibited by a TCAM function.
VT AM itself provides facilities for activating and deactivating terminals and lines from a system console. These commands can be used to prevent all data flow to or from a station.
The TCAM Release 5 operator commands that display which lines or stations are currently active or inactive are still available in a shared network but they display only the stations and lines activated or deactivated by TCAM for TCAM data. These commands do not display the status of lines and stations activated or deactivated by VT AM commands.
These commands are as follows:
• Display Active Stations
• Display Station Status and Message Numbers
• Display Intercepted Stations
• Display Inactive Line Entries
• Display Inactive Open Lines
• Display Line Status and Message Error Record
Certain TCAM Release 5 operator control functions arc replaced in the VT AM/TeAM shared environment by VTAM functions which are available from a system console, and not from TCAM operator control stations or TCAM application programs. The replaced TCAM operator commands are as follows:
• Display 3705 Status
• Activate a 3705
• Deactivate 3705 Line and Terminal
fit Dump 3705 Storage
• IPL a 3705
• PEP Switch Line Mode
• Start/Stop BTU Trace
• Change NCP Load Module
• Change Session Limit
• Change 3705 Transmission Limit
• Activate/Deactivate Line Trace
• Change Polling Delay Duration
Chapter 7. VTAM Planning Considerations and Requirements 185
TeAM Operator Messages Replaced with VT AM Operator Messages
DOS/VS Coexistence
In the vr AM/TCAM shared network, vr AM awareness messages replace the TCAM operator awareness messages present in OS/VS TCAM Release 5. TCAM may route the Release 5 operator awareness messages to operator control stations and TCAM application programs, but the vr AM . awareness messages that replace them are directed to a system console. (An installation-designated console can be used in conjunction with MCS and an installation-supplied WTOR exit routine. See Note 2.)
Awareness messages deal with:
• Channel operations
• NCP status
• Line and terminal errors
Replies to TCAM operator commands continue to be routed to the TCAM operator control stations or TCAM application programs that enter the commands. Additionally, the TCAM ERRORMSG message handler macro instruction can be used to route information to TCAM application programs.
Note 1: The following TCAM operator commands and macro instructions still exercise some degree of physical control over the shared network, and their effect on the VT AM portion of the network should be considered before they are issued:
• Change 3705 Line Speed.
• Switch 3705 Devices (dial backup for non-SDLC leased lines). If using this TCAM feature, do not use vr AM operator commands to activate or deactivate the lines to these devices.
• TCHNG
• ICHNG
Note 2: In the above discussion of TCAM operator commands, the term "a. system console" denotes either the operating system console or a Multiple Console Supported (MCS) terminal. For details of Multiple Console Support, see the OS/VS VTAM System Programmer's Guide.
In a DOS/VS system, QTAM, BTAM, and VTAM can operate concurrently. QTAM and BT AM programs do not interact with vr AM. QT AM programs use QTAM, and BT AM programs use BTAM to communicate with:
• Terminals attached to transmission control units
• Terminals attached to communications controllers by line in emulation mode
• Terminals attached locally (BT AM only)
VT AM application programs use VT AM to communicate with:
• Terminals attached to communications controllers by lines in network control mode
• 3270 terminals attached locally
• 3790 terminals attached locally
Lines attached to communications controllers using the NCP with PEP can be used in either network control or emulation mode with an appropriate access method.
Figure 7-8 illustrates concurrent use ofQTAM, BTAM, and vrAM in DOS/VS.
Host CPU
Commun ications Controller in Emulation Mode
OTAM Programs
OTAM
VTAM Programs
"
Transmission Control Unit (2701,2702, or 2703)
"
Communications Controller in Network Control Mode
VTAM
Figure 7-8. DOS/VS Coexistence
"
"
Transmission Control Unit (2701, 2702, or 2703)
Local 3270 or Local 3790
BTAM Programs
BTAM
"
,f
Communications Controller in Emulation Mode
Local Terminals
Chapter 7. VTAM Planning Considerations and Requirements 187
Host CPU
TCAM VTAM BTAM
Programs Programs Programs
t
TCAM
- -
VTAM BTAM"
,11
" "
Communications
Local Local Communications
Controller in
Terminals TerlTlinals Controller in
Emulation Mode Emulation Mode
"
~f
" 'W
Transmission Communicati ons Transmission
Control Unit Controller in Local Control Unit
(2701, 2702, Network Control Terminals 1 (2701, 2702,
or 2703) Mode or 2703)
1 VTAM programs can communicate locally with 3270 and 3790 terminal systems. TCAM programs using VTAM can communicate locally with 3270 terminal systems.
Figure 7-9. OS/VS Coexistence