Here is the usage description from the Pro*COBOL Programmer's Guide:
DB2 provides an assembler routine called DSNTIAR to obtain a form of the SQLCA that can be displayed. For users migrating to Oracle from DB2, Pro*COBOL provides DSNTIAR. The DSNTIAR implementation is a wrapper around SQLGLM. The DSNTIAR interface is as follows
CALL 'DSNTIAR' USING SQLCA MESSAGE LRECL
where MESSAGE is the output message area, in VARCHAR form of size greater than or equal to 240, and LRECL is a full word containing the length of the output messages, between 72 and 240. The first half-word of the MESSAGE argument contains the length of the remaining area. The possible error codes returned by DSNTIAR are listed in the following table.
Error Codes Description
More data was available than could fit into the provided message
The logical record length (LRECL) was not between 72 and 240
The message area was not large enough (greater than 240)