Overview of CMS/DOS
CMS/DOS is neither CMS nor is it DOS. It is a composite, and its vocabulary contains both CMS and VSE terms. CMS/DOS performs many of the same functions as DOS. However, under VSE a function is initiated by a control card, while under CMS it is initiated by a command. Many CMS/DOS commands, therefore, have the same names as the VSE control statement that performs the same function. In those cases where the control statement you would use in VSE and the command you use in CMS are different, the differences are explained. In general, whenever a term that is familiar to you as a VSE term is used, it has the same meaning to CMS/DOS, unless otherwise indicated.
CMS/DOS support in z/VM is based on the VSE licensed program. The term DOS, however, continues to be used in a general sense, and in the discussion that follows, DOS refers to the VSE licensed program.