TSO/VTAM support of 3270 devices

TSO/VTAM supports the following two types of 3270 devices:

Non-SNA devices attached locally or by a bisynchronous line protocol
SNA devices attached by SDLC links

If no logon mode table entry exists for a 3270 device, TSO/VTAM assumes that the device is non-SNA (LU0) and uses the buffer size in the SCRSIZE parameter of the TSOKEY00 parmlib member. The following are valid values for the SCRSIZE parameter:

480 [ 12x40]
1920 [ 24x80]
2560 [ 32x80]
3440 [ 43x80]
3564 [ 27x132]
9920 [ 62x160]

For non-SNA devices with different screen sizes or special features and for SNA devices (LU2), you need to provide a logon mode table entry.

Use the MODETAB and MODEENT macroinstructions to define 3270 characteristics in logon mode tables and their entries. The PSERVIC operand of the MODEENT macroinstruction defines device LU type, buffer sizes, single-byte language, and QUERY capability (that is, programmed symbol sets, extended color, extended data stream, or extended highlight support). The LANG operand of the MODEENT macroinstruction defines the single-byte language of the device and whether it should be queried for double-byte capability.

Following are examples of definitions of MODEENT table entries.