All available address space (XS) can be used in UDS/SQL.
UDS/SQL tasks of the independent DBH are always executed in addressing mode (AMODE) 31.
UDS/SQL code in user tasks (e.g. the UDS/SQL connection) and in the linked-in DBH is executed in the AMODE of the application program that issues the DML request. In the linked-in DBH, the AMODE must not be modified dynamically in an application program run for the DML requests.
User code that is directly entered during DML processing (e.g. the DSCEXT error handling routine of CALL DML) must be executable in the AMODE of the DML request.
It is generally advisable to make all application programs XS-compatible and to run them in AMODE 31. This will avoid the problem of address space restrictions when more complex and extended functionality is introduced in the applications.