You can use the numeric class test to perform data validation. For example:
LINKAGE SECTION.
01 COUNT-X PIC 999.
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PROCEDURE DIVISION USING COUNT-X.
IF COUNT-X IS NUMERIC THEN DISPLAY "DATA IS GOOD".
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The numeric class test checks the contents of a data item against a set of values that are valid for the particular PICTURE and USAGE of the data item. For example, a packed decimal item would be checked for hexadecimal values X'0' through X'9' in the digit positions, and for a valid sign value in the sign position (whether separate or non-separate).
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