When the list form of the GETLINE macro instruction expands, it builds a two word GETLINE parameter block (GTPB). The list form of the macro instruction initializes this GTPB according to the operands you have coded in the macro instruction. This initialized block, which you can later modify with the execute form of the macro instruction, indicates to the GETLINE service routine the function you want performed.

You must supply the address of the GTPB to the execute form of the GETLINE macro instruction. For non-reentrant programs you can do this simply by placing a symbolic name in the symbol field of the list form of the macro instruction, and passing this symbolic name to the execute form of the macro instruction as the PARM value. The GETLINE parameter block is defined by the IKJGTPB DSECT, which is provided in SYS1.MACLIB. Table 1 describes the contents of the GTPB.