Certain environment variables can affect or tune the behavior of the library. The variables and their behavior are described here.
BOTAN_THREAD_POOL_SIZEcontrols the number of threads which will be created for a thread pool used for some purposes within the library. If not set then it defaults to the number of CPUs available on the system.
BOTAN_MLOCK_POOL_SIZEcontrols the total amount of memory which will be locked in memory using
VirtualLockand managed in a memory pool. If set to
0(or indeed any value smaller than the system page size), then the memory pool is disabled.
BOTAN_FFI_PRINT_EXCEPTIONSif this variable is set (to any value), then if an exception is caught by the FFI layer, before returning an error code, it will print the text message of the exception to stderr. This is primarily intended for debugging.