gtpi1m4iSystem Installation Support Reference

Select A Host

The select a host user exit, UAPN, allows you to select the TPF processor in the loosely coupled complex to assign to a new LU-LU session. UAPN is also valuable in a uniprocessor TPF environment because it allows you to select a path (link) for the session.

The TPF system invokes UAPN when a session activation request (LOCATE command) is received on the CP-CP sessions.

Input

R1
RVT1 address of the remote LU

R2
RVT1 address of the local TPF LU

R5
Pointer to the table containing active links for the TPF loosely coupled complex. The ITAPST DSECT maps out the entries in this table.

EBW000
Indicator byte (zero or more bits can be set)

X'80'
The TPF LU is processor-unique, or the remote LU is an LU 6.2 node that already has one or more sessions with a TPF processor; therefore, the TPF processor has been selected.

X'40'
The APPN network provided a suggested route for the LU-LU session.

EBW001
The CPU ID of the selected or suggested TPF processor. The value of this field is based on the value of the EBW000 field as follows:

EBW010-EBW017
Mode name of the session

EBW020-EBW027
The ALS name of the suggested link. This field is defined only when bit X'40' in field EBW000 is set.

Programming Considerations

Return Values

EBW002
Option chosen by the user exit:

0
The user exit did not select a TPF processor or a link. If the TPF system has not already selected the TPF processor (EBW000 bit X'80' is not set), the default logic in the TPF system will be used to select a TPF processor. Regardless of the value of field EBW000, the APPN network will select the link.

1
The user exit selected a TPF processor and, optionally, a link.

If the TPF system has not already selected the TPF processor (EBW000 bit X'80' is not set), field EBW001 must contain the CPU ID of the TPF processor you selected. The processor you selected must be in CRAS state or above.

If you also selected a link, field EBW020-EBW027 must contain the name of the selected ALS.

2
The user exit chose to use the suggested path. This return code is valid only if EBW000 bit X'40' was set on input to UAPN.

EBW001
CPU ID of the selected TPF processor.

EBW020-EBW027
ALS name of the link selected for the LU-LU session.