For OPEN MODEs used to open a data set, the following macros are defined in the tfcd.h header file.

#define TFCD_OPEN_INPUT             0   /* OPEN INPUT */
#define TFCD_OPEN_OUTPUT            1   /* OPEN OUTPUT */
#define TFCD_OPEN_INOUT             2   /* OPEN I-O */
#define TFCD_OPEN_EXTEND            3   /* OPEN EXTEND */

When a data set is opened successfully, 00 is stored in the status code which can be checked with tfcd_get_status(). If you try to reopen a data set which is already opened, an error occurs.

When a data set is closed successfully, 00 is stored in the status code which can be checked with tfcd_get_status(). Once closed, a data set can be opened again by using the tfcd_open() API.

When executing the START API, it can be specified to find records with key values that are the same as or larger than the key value specified using the following macros defined in the tfcd.h header.

#define TFCD_START_DEFAULT          0   /* START */
#define TFCD_START_EQUAL            1   /* START (equal to full length) */
#define TFCD_START_GTEQ             2   /* START (not less than) */

For a VSAM data set, ALTERNATE RECORD KEY can be defined in addition to the basic RECORD KEY of the data set. To execute the START API by using the ALTERNATE RECORD KEY, call the tfcd_set_key_id() API and specify the KEY ID that is used in the next START API. KEY IDs are assigned in the order that the ALTERNATE RECORD KEYs are specified in the SELECT statement of the main COBOL application.

For a VSAM data set, ALTERNATE RECORD KEY can be defined in addition to the basic RECORD KEY of the data set. To read records randomly by using the ALTERNATE RECORD KEY, call the tfcd_set_key_id() API and specify the KEY ID that is used in the next READ API. For KEY IDs, numbers are given in the order that the SELECT statement specified ALTERNATE RECORD KEYs in the main COBOL application.

Macros, which define whether to read records sequentially or randomly when executing the READ API, are defined as follows in the tfcd.h header file.

#define TFCD_READ_DEFAULT           0   /* READ */
#define TFCD_READ_NEXT              1   /* READ (sequential) */

For a variable length record data set, when reading data set records by using the READ API, the record length that was read can be obtained by calling the tfcd_get_rec_len() API. The record length obtained is the length of the record data excluding RDW.

Writes a record at the end of the data set for a sequential data set. For a RELATIVE data set, call the tfcd_set_relative_key() API and specify the relative record number to be stored. For an INDEXED data set, records are stored according to the order of keys within the record pointer.

The macros, which decide whether to write a new record or overwrite the existing record when executing the WRITE API, are defined as follows in the tfcd.h header file.

#define TFCD_WRITE_DEFAULT          0   /* WRITE */
#define TFCD_WRITE_REWRITE          1   /* REWRITE */

For a variable length record data set, the record length can be specified by calling the tfcd_set_rec_len() API before writing data set records with the WRITE API. The record length is the length of the record data excluding RDW.

#define TFCD_WRITEA_AFTER           0   /* AFTER */
#define TFCD_WRITEA_BEFORE          1   /* BEFORE */

#define TFCD_WRITEA_TAB             2   /* TAB */
#define TFCD_WRITEA_PAGE            4   /* PAGE */
#define TFCD_WRITEA_MNEMONIC        8   /* MNEMONIC */

If a critical system error or OpenFrame library error occurs while performing I/O on a data set, the program terminates and shows an error message. However, for general data set I/O errors, such as END OF FILE, the program does not terminate and the I/O function returns normally after setting the proper status code value. After executing an I/O function, it is necessary to check if an error occurred through the tfcd_get_status() function.

For a variable length record data set, the record length is the length of the record data excluding RDW.

To read records randomly by using ALTERNATE RECORD KEY on a data set with ALTERNATE RECORD KEY additionally defined, call the tfcd_set_key_id() API and specify the KEY ID to use in the next READ API.

For a variable length record data set, the record length is the length of the record data excluding RDW.