Considerations for developing 64-bit applications

Using compiler options to build 64-bit applications
To compile code for 64-bit applications, you must use the LP(64) compiler option. You must be aware that under LP(64), some compiler options or suboptions are not supported, and that some options or suboptions are ignored during compilation.

Using attributes HANDLE and POINTER under LP(64)
The default size and alignment of HANDLE and POINTER under LP(64) are different from the default under LP(32).

Using ENTRY variables under LP(64)
Under LP(64), all ENTRY variables, whether they have the LIMITED attribute or not, are eight bytes in size and are by default doubleword-aligned. Therefore, a structure that contains an ENTRY variable might now have padding bytes.

Using built-in functions under LP(64)
When you develop 64-bit applications, you must be aware that the argument and return types of some built-in functions are different.

Considerations for SQL programs
To use the same source to develop 32-bit and 64-bit applications, it is recommended that you declare sqlda or sqlda2 by using the EXEC SQL INCLUDE statement, and that the sqldabc field be set to use stg(sqlvar(1)) as the size of sqlvar. If your SQL program is not following these recommendations, you might need to change your code to develop a 64-bit application.

Communicating with 31-bit routines