Build vector (X'02')

The exit returns the build vector to VTAM® in response to being called by the XID vector (X'01'). The exit must return the address of the build vector in register 1 of the configuration services XID exit routine output parameter list; the exit also must return a return code.

The CSISP macrolibrary is needed to assemble the XID exit routine. The CSISP macrolibrary must be the first macrolibrary in the global macrolibrary list. See Installing VTAM exit routines for more information.

If the exit is called for dynamic builds and VTAM is to process the REQCONT (or REQACTPU for DLUS resources), the build vector returns model PU and LU names and real PU and LU names for VTAM to use when defining the switched resource. The build vector also returns the major node name, when appropriate, under which the dynamic switched resource will be added. If the exit expects dynamic builds to occur, the X'80' bit of byte 0 of the build vector must be 0 and there must be resource entry blocks for each dynamic device.

For a description of how the sample exit identifies the switched resource and generates a valid unique name for the resource, see Sample configuration services XID exit routine.

If the exit routine requests that VTAM call the exit when VTAM receives a REQCONT (or a REQACTPU for DLUS-supported resources), for a PU that is already defined, VTAM calls the exit with an XID vector whenever a known PU attempts to dial in. The exit must return a build vector that indicates whether VTAM is to allow the connection. If VTAM allows the connection, and the device is already defined, there is no need for any resource entry blocks. In this situation, VTAM ignores any resource entry blocks that might be contained in the build vector.

Table 1. Build vector format
Dec (Hex) offset	Size (Bytes)	Description
0 (0)	1	Flag byte (Bit Setting) B'1... ....' Indicates whether VTAM is to process the REQCONT (or the REQACTPU for DLUS-supported devices). If this bit is on, VTAM does not process the REQCONT or the REQACTPU. B'.... ...1' Indicates whether an 8-character major node name follows this flag byte. The remaining bits are reserved.
This field contains one of the following indications based on whether a major node name is supplied in the build vector:
1 (1)	8	This is the 8-byte name of the dynamic switched major node under which the resources defined in the resource entry blocks that follow the build vector will be added. If the named major node does not exist, it will be created by VTAM.
0 (0)	1	This is byte 0 of the first resource entry block.