Reading Records from a VSAM File

   Use the READ statement to retrieve (READ) records from a file.  To read a

   record, you must have opened the file INPUT or I-O.  You should check the

   file status key after each READ statement.

   Records in VSAM sequential files can be retrieved only in the sequence in

   which they were written.

   Records in VSAM indexed and relative files can be retrieved:

   Sequentially

       According to the ascending order of the key you are using, the RECORD

       KEY or the ALTERNATE RECORD KEY, beginning at the current position of

      the file position indicator for indexed files, or according to

       ascending relative record locations for relative files.

   Randomly

       In any order, depending on how you set the RECORD KEY or ALTERNATE

       RECORD KEY prior to your READ request.

   Dynamically

       Mixed sequential and random.

   With dynamic access, you can switch between reading a specific record

   directly and reading records sequentially, by using READ NEXT for

   sequential retrieval and READ for random retrieval (by key).  See "File

   Access Modes"  for a complete description of the features of

   each access mode.

   When you want to read sequentially, beginning at a specific record, use

   START before the READ NEXT to set the file position indicator to point to

   a particular record.

   When you specify START followed by READ NEXT, the next record is read and

   the file position indicator is reset to the next record.  The file

   position indicator can be moved around randomly through the use of START,

   but all reading is done sequentially from that point.  You can continue to

   read records sequentially, or you can use the START statement to move the

   file position indicator:

     START file-name KEY IS EQUAL TO ALTERNATE-RECORD-KEY

   When a direct READ is executed, based on an alternate index for which

   duplicates exist, only the first record in the data set (base cluster)

   with that alternate key value is retrieved.  You need a series of READ

   NEXT statements to retrieve each of the data set records with the same

   alternate key.  A FILE STATUS value of '02' is returned if there are more

   records with the same alternate key value to be read; a value of '00' is

   returned when the last record with that key value has been read.