Explanation

The APPROVAL attribute specifies a procedure that can prevent linkage from occurring if the matching library is unauthorized. Additionally, the APPROVAL procedure can select the connection number to be used.

The person who implements the library program is responsible for writing this procedure (hereafter referred to as the APPROVAL procedure).

If there is an APPROVAL procedure for a connection library, the APPROVAL procedure must be declared outside the connection block for that library.

The APPROVAL attribute can be assigned to the connection library on either side of a connection. That is, an APPROVAL attribute can be specified in a connection library declaration regardless of whether that connection library is to be used in READYCL or LINKLIBRARY functions.

If both ends of a connection specify APPROVAL procedures, then the APPROVAL procedure declared by the process requesting the LINKLIBRARY is executed first, followed by the APPROVAL procedure declared by the process that performed the READYCL. Both APPROVAL procedures can optionally select a connection index; each connection index applies to the side of the connection that executes the APPROVAL procedure.

If an error or fault occurs in an APPROVAL procedure, the system prevents the linkage from completing. However, neither the linking process nor the library being linked to incurs an error.

Default

If no APPROVAL procedure is specified, then permission for the linkage is granted and the operating system selects the connection to use for the linkage.

MYSELF Task Variable

Currently, when the MYSELF task variable is used inside an APPROVAL procedure, MYSELF refers to the process that initiated the linkage. This process is not necessarily the declarer of either library involved in the linkage.

Direct Library Linkages

If a process uses direct linkage to link two libraries, the system does not execute the APPROVAL procedure for either library unless it is necessary to resolve the connection index. That is, the system executes the APPROVAL procedure for either library only if that library supports multiple connections and no connection index was specified in the LINKLIBRARY statement. For information about direct linkage, refer to Directly Linking Connection Libraries earlier in this section.

Initiating Library Linkages from the APPROVAL Procedure

In general, the system does not permit APPROVAL procedures to execute statements that cause a new library linkage to occur; such statements result in a failed linkage attempt. However, the system does permit APPROVAL procedures to link to certain system libraries such as GENERALSUPPORT and MCPSUPPORT. When a statement in an APPROVAL procedure links to a system library, the system does not execute any CHANGE or APPROVAL procedure that the linking process has declared for the system library itself.

Parameters and Return Value

The system passes parameters to the APPROVAL procedure that identify the other process involved in the linkage and the LIBPARAMETER, if any, specified by the linking process. The APPROVAL procedure returns a real result that indicates whether the linkage is to be allowed and, optionally, indicates which connection to use on the responding side.

The APPROVAL procedure must have the following form:

 REAL PROCEDURE APPROVAL (OWNER, LIBPAR, LEN, WAIT);
    VALUE        LEN, WAIT;
    TASK         OWNER;
    EBCDIC ARRAY LIBPAR[*];
    INTEGER      LEN;
    BOOLEAN      WAIT;

The APPROVAL procedure should read, but not modify, the procedure parameters. The following are the meanings of these parameters:

The result of the APPROVAL procedure is composed of the following fields: