1. A computer program product for modifying a virtual storage access method (VSAM) data set during open time, the computer program product comprising a computer readable storage medium having computer readable program code embodied therewith, the embodied computer readable program code comprising: computer readable program code configured to open a VSAM data set; and computer readable program code configured to modify a VSAM control block structure for the VSAM data set while the VSAM data set is open during an open time in which static data set characteristics and/or job parameters have been defined for the VSAM data set, wherein the computer readable program code configured to modify the VSAM control block structure comprises computer readable program code configured to interact with the VSAM data set within a VSAM dynamic address space using at least one of: a VSAM console interface and a VSAM programming interface.