sap abap program for Prevent program from having more than one instance running at the same time

REPORT ZPROGRAM.

*******************************************************************************
* Prevent the program from having more than one instance running the same time.
* Create this macro in TRMAC using SM31
* Insert the following single line in the program right after the
* REPORT statement: ZCHK_MYSELF_RUNNING SY-REPID.
*******************************************************************************

define my_macro.

DATA: PRG LIKE INDX-SRTFD.
PRG = &1.

CALL FUNCTION 'ENQUEUE_ESINDX'
EXPORTING
RELID = 'ZZ'
SRTFD = PRG
SRTF2 = 0
EXCEPTIONS
FOREIGN_LOCK = 1
SYSTEM_FAILURE = 2.
IF SY-SUBRC NE 0.
WRITE: 'ERROR:', PRG, 'is already running'.
EXIT.
ENDIF.

end-of-definition.

my_macro 'ZPROGRAM'.