The function VALUE fails with the error REX0040E (Incorrect call to routine) if you're trying to change the contents of an environment variable and the length of the value of another environment variable is greater than 725.
Source: Mario Semo (see EMail Addresses)
[Fixed in OBJREXX 6.00 26 Feb 1997 and newer versions (included in WARP
4 Fixpack #6)]