Example: MODCB macro (modify a request parameter list)

In this example, a MODCB macro is used to modify the record length field in a request parameter list.

This example shows the one exception to GENCB, MODCB, SHOWCB, and TESTCB building a parameter list and passing it to the control block manipulation module in register 1. The RPL address (in register 2) is loaded into register 1 and the RECLEN value (in register 3) is loaded into register 0. These registers are passed to the control block manipulation macro. This occurs when the LIST, EXECUTE, or GENERATE form of the MODCB macro is not used and the only parameter specified other than RPL, is RECLEN.

        L      3,length      Load the new record length.
 
        MODCB  RPL=(2),      Register 2 contains the address           x
                             of the request parameter list.            x
               RECLEN=(3)    Register 3 contains the record length.

The MODCB macro's parameters are:

RPL specifies register 2 contains the address of the request parameter list being modified.
RECLEN specifies the record length field is being modified. The contents of register 3 replace the current value in the RECLEN field.