MSS emulates those MVS control blocks that are accessible to applications running in problem program state. The information stored in these control blocks is limited to that which has value and meaning to applications running in problem program state.
The MVS control blocks are constructed using the default program attributes of the SSTM, which are a mainframe dialect, AMODE(31), and a character set derived from the value of the environment variable MF_CHARSET. If this variable is not set, then a value of ASCII is used. This means that the pointers to the sub-block areas are in mainframe format, rather than native format.
Control blocks are accessed in MSS in the same way as they are on a mainframe, by referencing the appropriate field in the Communication Vector Table (CVT). The address of the CVT is stored at absolute address 16 in memory, as it is on the mainframe.