gtps2m2sACF/SNA Data Communications Reference

Session Status Awareness Services

A TPF application may require knowledge of LU session establishment and/or termination in order to determine whether to transmit, queue, or purge the output for that resource. You can specify session awareness support for LU sessions in the RSC statement of the OSTG input data set or by using the Dynamic LU user exit.

A 3270 welcome screen is also available through session awareness support for 3270 sessions. The TPF system provides a sample 3270 welcome screen. You can modify this sample to meet your needs.

See TPF System Installation Support Reference for more information about the Dynamic LU user exit and the sample 3270 welcome screen. See TPF ACF/SNA Network Generation for more information about the RSC statement and the OSTG program.

Activating Session Status Awareness Services

If this notification is implemented, ENTRC activates CSXD with notification information for the following events:

To notify the application/user of these events, TPF code passes the information to CSXD with the address of the ISHLL area contained in register 1. The fields for each event parameter list are described in Table 10.

The released CSXD module contains a BACKC instruction.

Table 10. CSXD Interface

Interface Input to CSXD Returned from CSXD
Registers R1: ISHLL ADDR R0-R7: Not changed
ECB Workarea
  • EBW000-EBW103: Reserved
  • EBSW01-3: Reserved
  • EBRS01: Reserved
  • EBCM01-3: Reserved
  • EBER01: Reserved
  • EBX000-EBX023: ISHLL
  • EBX024-EBX103: Irrelevant

  • EBW000-EBW103: Unchanged
  • EBSW01-3: Unchanged
  • EBRS01: Unchanged
  • EBCM01-3: Unchanged
  • EBER01 Unchanged
  • EBX000-EBX023: Irrelevant
  • EBX024-EBX103: Irrelevant

Data Levels
  1. D0-D7: not available
  2. D8-DF: available

Same as on input.
Protect Key Working Storage Working Storage

Starting Session Started Notification

Notification of this event is driven whenever TPF data flow is enabled for an SNA session. The TPF application can now send messages on this session. Any messages already on the TPF OMT queue are also sent.

When data flow is enabled, OMT processing issues an ENTRC to start the user replaceable module (CSXD) with the address of the Session Started Notification Interface in register 1. (See Table 11 and Table 10 for detailed information.) Labels for this area are defined using the ISHLL macro.

Table 11. Session Started Notification Interface

Label Length (In Bytes) Description
ISHLNOT 1 X'05' Session Started Notification
ISHLSS 1 Reserved (X'00' only value defined).
ISHLRC 1 Reserved (X'00' only value defined).
ISHLSW 1 Reserved (X'00' only value defined).
ISHLSNAM 4 Secondary LU Name Address

The address of a 16-byte field that contains the NETID and the Network Qualified LU name of the resource functioning as secondary LU (SLU) for the requested session. The NETID is an 8-character string left-justified and padded with blanks. The name, which immediately follows the NETID, is also an 8-character string left-justified and padded with blanks.

ISHLPNAM 4 Primary LU Name Address

The address of a 16-byte field that contains the NETID and the Network Qualified LU name of the resource functioning as primary LU (PLU) for the requested session. The NETID is an 8-character string left-justified and padded with blanks. The name, which immediately follows the NETID, is also an 8-character string left-justified and padded with blanks.

ISHLPSV 6 Process Selection Vector.

Left-justified 6-character PSV name, padded with blanks, defined for the remote LU.

Starting Session Ended Notification

This event indicates that the session is no longer available for data transmission to or from the TPF application.

Notification of this event is driven whenever a session between a TPF application and a network resource is terminated. Possible reasons for this event and session outages are normal session termination and network failure.

When the session ends, Lost Terminal Processing issues an ENTRC to start the user replaceable module (CSXD) with the address of the Session Ended Notification Interface in register 1. (See Table 10 and Table 12 for additional information.) Labels for this area are defined using the ISHLL macro.

Table 12. Session Ended Notification Interface

Label Length (In Bytes) Description
ISHLNOT 1 X'06' Session Ended Notification
ISHLSS 1 Session Status at time of failure.
  1. X'01' - Pending activation
  2. X'02' - In session and data flow allowed
ISHLRC 1 Reserved (X'00' only value defined).
ISHLSW 1 Reserved (X'00' only value defined).
ISHLSNAM 4 Secondary LU Name Address

The address of a 16-byte field that contains the NETID and the Network Qualified LU name of the resource functioning as secondary LU (SLU) for the requested session. The NETID is an 8-character string left-justified and padded with blanks. The name, which immediately follows the NETID, is also an 8-character string left-justified and padded with blanks.

ISHLPNAM 4 Primary LU Name Address

The address of a 16-byte field that contains the NETID and the Network Qualified LU name of the resource functioning as primary LU (PLU) for the requested session. The NETID is an 8-character string left-justified and padded with blanks. The name, which immediately follows the NETID, is also an 8-character string left-justified and padded with blanks.

ISHLPSV 6 Process Selection Vector.

Left-justified 6-character PSV name, padded with blanks, defined for the remote LU.