k5_size_context
k5_size_context(krb5_context context, size_t *sizep);
kret = k5_size_context(ctx->k5_context, &required);
if ((kret = k5_size_context(context, &required)))
check(k5_size_context(ctx, &elen));
check(k5_size_context(ctx2, &elen2));