Resource entry blocks

There is a resource entry block for each LU contained in the device that powered on. For the resource entry blocks that have the REBERROR bit set to 0, the exit is responsible for ensuring that the resource entry block contains a model LU name and a valid VTAM® name for the LU.

If the REBDEFND bit is set to 1, the resource entry block represents the redefinition of an existing LU. In this case, the LU name is already in the REBNAME field and cannot be changed by the exit. If the REBDEFND bit is set to 0, the resource entry block represents the definition of a dynamic LU that has not yet been named. The exit must generate an LU name and place it in the REBNAME field.

The REBMODEL field of the resource entry block contains the model acronym of the device that powered on. The exit can use the model acronym or override it with another model name from the model LU group specified on the PU definition statement for the device the dynamic definition request represents.

The format of a resource entry block is described in Table 1.

Table 1. SDDLU resource entry block format
Dec (Hex) offset	Size (Bytes)	Symbolic name	Description
0 (0)	1	REBTYP	Resource type This is always X'01' for the SDDLU exit, which indicates the resource is an LU.
1 (1)	1		Resource entry block flags
		REBADOV	These bits are reserved.
		REBERROR	B'.1.. ....' If this bit is set to 1 when the exit is called, this resource entry block does not represent a valid LU definition and must be ignored by the exit. If the exit sets this bit to 1, VTAM will not define the LU represented by this resource entry block.
		REBDEFND	B'..0. ....' This resource entry block is for an LU that has not been defined previously at the local address. The exit must generate an LU name to be assigned to the LU. B'..1. ....' This resource entry block redefines an LU that was defined previously. The name of the LU is in the REBNAME field and the exit cannot change it. The remaining bits are reserved.
		REBLUNMF	B'..1. ....' This resource entry block contains an LU encryption key name field, REBLUKNM.
2 (2)	8	REBNAME	Name of dynamic resource If the REBDEFND bit is set to 0, this resource entry block represents the definition of a new LU. The exit must generate an LU name to be assigned to the LU. If the REBDEFND bit is set to 1, this field contains the current name of the LU. The exit cannot change this name.
10 (A)	8	REBMODEL	Model LU name VTAM uses this model name to select the model LU definition from the model LUGROUP operand specified on the PU's definition statement. On input, this field contains the model acronym of the device this dynamic definition request represents. The default exit does not modify this field. The exit uses this model acronym as the name of the model LU VTAM uses to define the LU. A user-written exit can use the model acronym supplied on input, or change this field to any model LU name from the model LU group for the device this dynamic definition request represents.
18 (12)	1	REBADDR	Local address of the LU being defined
19 (13)	8	REBLUKNM	Name of the LU encryption key. If the REBLUNMF bit is set to 1, this field is defined and is initialized to hex zeros. If the field is changed from hex zeros, VTAM uses this as the name of the LU's encryption key. If the field is not changed, the LU encryption key name defaults to the LU name. If the REBLUNMF bit is set to 0, this field is not defined and the LU encryption key name defaults to the LU name.