In addition to the PL/I input and output statements  and  functions
  and  features  available  through  the  options  of the ENVIRONMENT
  attribute,  there  are  several  built-in  subroutines.   They  are
  "built-in"  because  you  do  not need to declare them before using
  them in a PL/I program.

1 - DISPLAY

  Obtains information about a given file.

  CALL DISPLAY (file-reference,variable-reference) ;

  The  variable  reference  must  have  an  identical  structure   as
  PLI_FILE_DISPLAY  in PLI$STARLET.TLB.  If PLI_FILE_DISPLAY is used,
  it must be allocated and associated with a pointer.

2 - EXTEND

  Increases a  disk  file's  allocation  by  a  specified  number  of
  512-byte disk blocks.

  CALL EXTEND (file-reference,integer-expression) ;

3 - FLUSH

  Writes RMS buffers back to disk and checkpoints the file.

  CALL FLUSH (file-reference) ;

4 - FREE

  Unlocks all the locked records in a specified file.

  CALL FREE (file-reference) ;

5 - NEXT_VOLUME

  Advances a magnetic tape file to the next volume.

  CALL NEXT_VOLUME (file-reference) ;

6 - RELEASE

  Unlocks a specified record in a file.

  CALL RELEASE (file-reference,variable-reference) ;

7 - RESIGNAL

  Handles  a  signaled  condition  by  continuing  the   signal   and
  requesting PL/I to locate another ON-unit to handle the condition.

  CALL RESIGNAL ();

8 - REWIND

  Rewinds a tape volume to its beginning or positions a disk file  at
  the  first  record  in  the  file  or  the  first record in the key
  sequence.

  CALL REWIND (file-reference);

9 - SPACEBLOCK

  Repositions a file that is opened for block I/O forward or backward
  by a specified number of blocks.

  CALL SPACEBLOCK (file-reference,integer-expression);