Z doesn't really have files or databases, but rather an emulation of variable-length records contained within a relatively fixed allocation on disk. Mainframe D

Z doesn't really have files or databases, but rather an emulation of variable-length records contained within a relatively fixed allocation on disk. Mainframe DASDs also have a much richer interface than just read/write a given block; for example, you can scan for records within a track that have a given prefix