The BLOCK CONTAINS clause specifies the size of a physical record.

  Format -

   BLOCK CONTAINS [smallest-block TO] blocksize { RECORDS    }
                                                { CHARACTERS }

1  –  smallest-block

  is an integer literal.  It specifies the minimum physical record
  size.

2  –  blocksize

  is an integer literal.  It specifies the exact or maximum physical
  record size.