Using the DSECTs

Having used the DSECT-creating macroinstructions to define one or more control-block maps, the program can obtain storage for a control block from an assembled pool or dynamically from the system. The address of this storage should be placed in a register and specified in a USING statement before setting or testing values using the statements generated by the macroinstruction. For example, suppose the address of an RPL is in register 5 and that, after a request containing data has been received, it is necessary to determine the value of the RECLEN field of the RPL.

allows assembler language instructions to refer to the label RPLRLEN to obtain the record length. Further information is in the introductory section of Control block formats and DSECTs.