Library /sys$common/syshlp/dbg$help.hlb DEBUG, DISABLE, AST, Example  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  DBG> DISABLE AST
  DBG> SHOW AST
  ASTs are disabled
  DBG>

      The DISABLE AST command disables the delivery of ASTs in your
      program, as confirmed by the SHOW AST command.