Historically, BSS (from Block Started by Symbol) was a pseudo-operation in UA-SAP (United Aircraft Symbolic Assembly Program), the assembler developed in the mid-1950s for the IBM 704 by Roy Nutt, Walter Ramshaw, and others at United Aircraft Corporation.[1][2] The BSS keyword was later incorporated into FAP (FORTRAN Assembly Program), IBM's standard assembler for its 709 and 7090/94 computers. It defined a label (i.e. symbol) and reserved a block of uninitialized space for a given number of words (Timar 1996).

корни у названия древние... ИМХО связано с какими-то особенностями тачек того времени... вряд ли сейчас уже можно придумать какими именно...