Make PSK_LEN configurable and adjust PMS size
diff --git a/programs/ssl/ssl_client2.c b/programs/ssl/ssl_client2.c
index 3af54f9..4682ee5 100644
--- a/programs/ssl/ssl_client2.c
+++ b/programs/ssl/ssl_client2.c
@@ -325,7 +325,7 @@
     int ret = 0, len, server_fd, i, written, frags;
     unsigned char buf[SSL_MAX_CONTENT_LEN + 1];
 #if defined(POLARSSL_KEY_EXCHANGE__SOME__PSK_ENABLED)
-    unsigned char psk[256];
+    unsigned char psk[POLARSSL_PSK_MAX_LEN];
     size_t psk_len = 0;
 #endif
 #if defined(POLARSSL_SSL_ALPN)