diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 696a37b..d47d59e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -36,12 +36,22 @@ jobs:
         run: |
           docker tag opensourcecobol/opensourcecobol4j:"$version_string_prefix" opensourcecobol/opensourcecobol4j:latest
 
+      - name: Show Docker image size
+        run: |
+          docker images opensourcecobol/opensourcecobol4j:"$version_string_prefix" --format "table {{.Repository}}:{{.Tag}}\t{{.Size}}"
+
       - name: Check the version of installed software
         run: |
           docker run --rm opensourcecobol/opensourcecobol4j:latest sh -c "cobj --version | grep 'opensource COBOL 4J $opensource_COBOL_4J_version'"
           docker run --rm opensourcecobol/opensourcecobol4j:latest sh -c "! cobj --version | grep 'unicode/utf-8 support'"
           docker run --rm opensourcecobol/opensourcecobol4j:latest sh -c "ocesql --version | grep 'Version $Open_COBOL_ESQL_4J_version'"
 
+      - name: Run simple tests inside the container
+        run: |
+          docker run -itd --name test_container opensourcecobol/opensourcecobol4j:latest
+          docker exec test_container sh -c "cd /root/cobol_sample && cobj HELLO.cbl && java HELLO"
+          docker rm -f test_container
+
       - name: Login to Docker Hub
         if: github.ref == 'refs/heads/main' && github.event_name == 'workflow_dispatch' && inputs.push_to_dockerhub == true
         uses: docker/login-action@v3
@@ -73,11 +83,21 @@ jobs:
           docker build -t opensourcecobol/opensourcecobol4j:utf8-"$version_string_prefix" . -f utf8.Dockerfile \
           --build-arg opensource_COBOL_4J_version="$opensource_COBOL_4J_version"
 
+      - name: Show Docker image size
+        run: |
+          docker images opensourcecobol/opensourcecobol4j:utf8-"$version_string_prefix" --format "table {{.Repository}}:{{.Tag}}\t{{.Size}}"
+
       - name: Check the version of installed software
         run: |
           docker run --rm opensourcecobol/opensourcecobol4j:utf8-"$version_string_prefix" sh -c "cobj --version | grep 'opensource COBOL 4J $opensource_COBOL_4J_version'"
           docker run --rm opensourcecobol/opensourcecobol4j:utf8-"$version_string_prefix" sh -c "cobj --version | grep 'unicode/utf-8 support'"
 
+      - name: Run simple tests inside the container
+        run: |
+          docker run -itd --name test_container opensourcecobol/opensourcecobol4j:utf8-"$version_string_prefix"
+          docker exec test_container sh -c "cd /root/cobol_sample && cobj HELLO.cbl && java HELLO"
+          docker rm -f test_container
+
       - name: Login to Docker Hub
         if: github.ref == 'refs/heads/main' && github.event_name == 'workflow_dispatch' && inputs.push_to_dockerhub == true
         uses: docker/login-action@v3
diff --git a/Dockerfile b/Dockerfile
index a2e3e48..6d21e58 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,14 +1,14 @@
 # Build stage
-FROM almalinux:9 AS builder
+FROM almalinux:9-minimal AS builder
 
 ARG opensource_COBOL_4J_version=dummy_value Open_COBOL_ESQL_4J_version=dummy_value
 
 SHELL ["/bin/bash", "-c"]
 
 # install build dependencies
-RUN dnf update -y && \
-    dnf install -y gcc make bison flex automake autoconf diffutils gettext java-11-openjdk-devel && \
-    dnf clean all
+RUN microdnf update -y && \
+    microdnf install -y gcc make bison flex automake autoconf diffutils gettext java-11-openjdk-devel tar gzip && \
+    microdnf clean all
 
 # install sbt
 RUN curl -fL https://github.com/coursier/coursier/releases/latest/download/cs-x86_64-pc-linux.gz | gzip -d > cs && \
@@ -43,17 +43,17 @@ RUN cd /root/ && \
     rm -rf /root/Open-COBOL-ESQL-4j-${Open_COBOL_ESQL_4J_version}.tar.gz /root/Open-COBOL-ESQL-4j-${Open_COBOL_ESQL_4J_version}
 
 # Runtime stage
-FROM almalinux:9
+FROM almalinux:9-minimal
 
 ARG opensource_COBOL_4J_version=dummy_value Open_COBOL_ESQL_4J_version=dummy_value
 
 SHELL ["/bin/bash", "-c"]
 
 # install runtime dependencies only
-RUN dnf update -y && \
-    dnf install -y java-11-openjdk-devel && \
-    dnf clean all && \
-    rm -rf /var/cache/dnf/*
+RUN microdnf update -y && \
+    microdnf install -y java-11-openjdk-devel && \
+    microdnf clean all && \
+    rm -rf /var/cache/microdnf/*
 
 # create required directories
 RUN mkdir -p /usr/lib/opensourcecobol4j \
diff --git a/utf8.Dockerfile b/utf8.Dockerfile
index 5357d1b..2b7c750 100644
--- a/utf8.Dockerfile
+++ b/utf8.Dockerfile
@@ -1,14 +1,14 @@
 # Build stage
-FROM almalinux:9 AS builder
+FROM almalinux:9-minimal AS builder
 
 ARG opensource_COBOL_4J_version=dummy_value
 
 SHELL ["/bin/bash", "-c"]
 
 # install build dependencies
-RUN dnf update -y && \
-    dnf install -y gcc make bison flex automake autoconf diffutils gettext java-11-openjdk-devel && \
-    dnf clean all
+RUN microdnf update -y && \
+    microdnf install -y gcc make bison flex automake autoconf diffutils gettext java-11-openjdk-devel tar gzip && \
+    microdnf clean all
 
 # install sbt
 RUN curl -fL https://github.com/coursier/coursier/releases/latest/download/cs-x86_64-pc-linux.gz | gzip -d > cs && \
@@ -20,26 +20,34 @@ RUN cd /root && \
     curl -L -o opensourcecobol4j-v${opensource_COBOL_4J_version}.tar.gz https://github.com/opensourcecobol/opensourcecobol4j/archive/refs/tags/v${opensource_COBOL_4J_version}.tar.gz && \
     tar zxvf opensourcecobol4j-v${opensource_COBOL_4J_version}.tar.gz && \
     cd opensourcecobol4j-${opensource_COBOL_4J_version} && \
-    mkdir -p /tmp/usr/ &&\
-    ./configure --prefix=/tmp/usr/ --enable-utf8 && \
+    ./configure --prefix=/usr/ --enable-utf8 && \
     touch cobj/*.m4 && \
     make && \
     make install && \
     rm -rf /root/opensourcecobol4j-v${opensource_COBOL_4J_version}.tar.gz /root/opensourcecobol4j-${opensource_COBOL_4J_version}
 
 # Runtime stage
-FROM almalinux:9
+FROM almalinux:9-minimal
+
+ARG opensource_COBOL_4J_version=dummy_value
 
 SHELL ["/bin/bash", "-c"]
 
 # install runtime dependencies only
-RUN dnf update -y && \
-    dnf install -y java-11-openjdk-devel && \
-    dnf clean all && \
-    rm -rf /var/cache/dnf/*
+RUN microdnf update -y && \
+    microdnf install -y java-11-openjdk-devel && \
+    microdnf clean all && \
+    rm -rf /var/cache/microdnf/*
 
 # copy built files from builder stage
-COPY --from=builder /tmp/usr/ /usr/
+COPY --from=builder /usr/lib/opensourcecobol4j/ /usr/lib/opensourcecobol4j/
+COPY --from=builder /usr/bin/cob-config /usr/bin/cob-config
+COPY --from=builder /usr/bin/cobj /usr/bin/cobj
+COPY --from=builder /usr/bin/cobj-api /usr/bin/cobj-api
+COPY --from=builder /usr/bin/cobj-idx /usr/bin/cobj-idx
+COPY --from=builder /usr/bin/cobjrun /usr/bin/cobjrun
+COPY --from=builder /usr/include/libcobj.h /usr/include/libcobj.h
+COPY --from=builder /usr/share/opensource-cobol-4j-${opensource_COBOL_4J_version} /usr/share/opensource-cobol-4j-${opensource_COBOL_4J_version}
 
 # classpath settings
 ENV CLASSPATH=:/usr/lib/opensourcecobol4j/libcobj.jar