Restrictions on use of assembler features

The NCP and VTAM® definition statements are coded in standard operating system macroinstruction format, as described in Coding VTAM definitions, with the following restrictions:
  • You cannot use assembler program control instructions (such as ICTL and ISEQ) in groups of definition statements for major nodes.
  • You can use assembler listing control statements (such as PRINT, SPACE, and EJECT) in the NCP generation definition statements but not in those for the other types of major nodes.
The following assembler features cannot be used in a group statement for a major node:
  • Assembler macroinstructions that generate NCP definition statements
  • Names generated by global variables (such as &SYSNDX and &SYSECT)
  • Variable substitution at assembly time
  • References to assembler attributes (such as length and type)
  • Literals
  • Quoted strings
  • Null keywords; for example, two commas (,,) is treated as a null keyword and is not valid

You can use comments in groups of definition statements for all types of major nodes and PATH definition statements. However, do not use macroinstructions or operands, such as GENEND, especially in a continued line of comments.

Errors made in the groups of major node definition statements filed in the VTAM definition library result in messages to the system operator’s console during VTAM initialization or VARY ACT command processing.